Psych Stats Exams
A set of 30 exam scores with a mean of 60 and a standard deviation of 5 is converted to z-scores. What will be the standard deviation of the transformed scores?
1
A set of 30 exam scores with a mean of 60 and a standard deviation of 5 is converted to z-scores. What will be the variance of the transformed scores?
1
The probability of a 95% confidence interval including the SAMPLE MEAN is
1
In a population of N = 10 scores, the smallest score is X = 28 and the largest score is X = 40. The range for the population is __________.
12
which of these is the correct interpretation of the p value?
it shows the probability that you would have obtained the sample statistic's value or more extreme if the null were true
What type of scale of measurement doesn't involve measuring a quantity?
nominal
A researcher finds that neuroticism and self-reported number of close friends are significantly correlated, r = -.7. What is the effect size for this correlation?
0.49
A treatment is administered to a sample selected from a population with a mean of = 80 and a standard deviation of = 10. After treatment, the sample mean is M = 85. Based on this information, the effect size as measured by Cohen's d is
0.5
For Cohen's d, which of the following would be considered a moderate effect size?
0.51
In a normal distribution, what is the approximate probability of randomly finding a score between 2 standard deviations above and below the mean?
0.95
A population of scores has µ = 44. In this population, an X value of 40 corresponds to z = -4.00 What is the population standard deviation?
1
The distribution of sample means (for a specific sample size) consists of
all the sample means that could be obtained (for the specific sample size)
Which of the following statements about the alpha level of a hypothesis test is NOT true?
alpha level determines whether you are conducting a 1-tailed or 2-tailed test
confidence intervals most often used as
an inferential statistic to supplement null hypothesis testing
Which of the following accurately describes a hypothesis test?
an inferential technique that uses data from a sample to make conclusions about a population
A hypothesis test is
an inferential technique that uses the data from a sample to draw inferences about a population
Which of the following is an example of a continuous variable?
annual rainfall in a town
A researcher records if each participant is a parent or not. Which of the following is a level?
both a and b
An important concept in correlational research is that
correlation does not imply causation
A good example of descriptive statistics would be when you
create a bar graph that shows student average course evaluations for male and female instructors
a good example of descriptive statistics would be when you
create a bar graph that shows student average course evaluations for male and female instructors
The purpose of a scatterplot is to
create a graph of a relationship between two variables that visually represents both the direction and strength of the relationship
The owner of Dr. Rangelove's Stove Store wants to calculate what percentage of his ovens that he has sold are range stoves as opposed to another type. This is an example of a
descriptive statistic
What term is used to denote statistics that are only derived from the individuals in the study and not from the larger group of individuals that you, as the researcher, is interested in?
descriptive statistic
A researcher counts the number of faculty and the number of students who stop at a stop sign on campus. This is an example of
descriptive statistics
The owners of Cupid's Stupid Divorce Attorneys discover that they have won 0% of all their client's cases. This is an example of a
descriptive statistics
a researcher calculates the average reaction time (in milliseconds) for a visual stimulus and for an auditory stimulus. This is an example of
descriptive statistics
A doctor studies a very rare disease with only five known cases. The doctor wants to know the average age of onset of the disease and becasue he is the doctor for all five cases, he can simply look at their medical records. This doctor would likely perform.
descriptive statistics only
The most important reason for determining a variable's scale of measurement is to
determine which type of statistical analyses are appropriate to use
Why are deviation scores not useful measures of variability in a sample?
deviation scores across a sample will always add up to 0
______ allows researchers to describe (1) how far mean scores have shifted in the population or (2) the percentage of variance that can be explained by a given variable.
effect size
_______ allows researchers to describe (1) how far mean scores have shifted in the population or (2) the percentage of variance that can be explained by a given variable
effect size
You decide to collect information on weight for a sample of 500 people. Which type of graph would be best to use in this scenario?
either a histogram or frequency polygon
What z-score would a person need to score in the top 5% of all the scores?
greater than 1.65
The measure of central tendency that is the same as the 50th percentile is the
median
If high scores on one variable are associated with low scores on another variable, this indicates a
negative correlation
A population of scores has a mean of mean = 22, median = 23, and mode = 26. What is the most likely shape for the population distribution??
negatively skewed
On a particularly easy general psychology exam, most students got As and nearly everyone else got Bs. There were, of course, a few Cs and even fewer Ds and Fs. The shape of the distribution of scores could be described as
negatively skewed
Suppose a class takes a quiz and the majority of scores are high with fewer low scores. Which is the most likely shape of the distribution?
negatively skewed
What is the shape of the distribution for the following set of data? Scores: 1, 2, 3, 3, 4, 4, 4 5, 5, 5, 5, 6, 6, 6, 6, 6, 7
negatively skewed
A group of researchers believed people's perceived economic status (high or low) would cause changes in their support for political policies that redistributed income. What was their independent variable?
perceived economic status
A Pearson correlation of r = +0.85 indicates that a scatterplot would show
points clustered close to a line that slopes up to the right
a researcher reports that the size of an effect in Population A is d=0.10 and the effect size in Population B is d=0.34. which population is associated with greater power to detect an effect?
population B
Heavier vehicles require more breaking distance than lighter vehicles. The correlation between the two would be
positive
The average height for women in the US is about 5 ft 4 in. A woman who is 6 ft tall would have a z-score for height that is
positive
If high scores on one variable are associated with high scores on another variable, this indicates a
positive correlation
If low scores on one variable are associated with low scores on another variable, this indicates a
positive correlation
the most powerful way to create the groups for an independent samples t-test is to
randomly assign participants to two different groups
A researcher will conduct a survey about college students' political orientations. The easiest way to get a reprentative sample would be to
randomly select students to survey
Many physical dimensions such as height, depth and distance are _________ variables
ratio
The number of pets a person has represents which scale of measurement?
ratio
To assess students' interest in class lectures, an instructor tracks daily attendance. Attendance (number of days present) would be an example of what scale of measurement?
ratio
If the null hypothesis is outside the confidence interval, then the decision was likely to ______ using hypothesis testing
reject the null hypothesis
If the z score for your treated sample mean is NOT in the critical region, then the most appropriate statistical decision is to
retain the null hypothesis
What do descriptive statistics allow us to do?
summarize the characteristics of a sample of scores
The purpose of descriptive statistics is to
summarize the data that has been collected
Which of the following is most likely to be found if a sample is randomly drawn from a population?
the sample mean is .01 standard errors from the population mean
A sample of n = 25 individuals is selected from a population with mean = 80 and a treatment is administered to the sample. If the treatment has no effect, then
the sample mean should be close 80 and should lead you to fail to reject (retain) the null hypothesis
A sample of n=25 individuals is selected from a population with mean = 80 and a treatment is administered to the sample. If the treatment has no effect, then
the sample mean should be close 80 and should lead you to fail to reject (retain) the null hypothesis
If all the possible random samples of size = 10 are selected from a population of scores that is normally distributed with a µ = 80 and a δ = 10 and the mean is computed for each sample, then what shape is expected for the distribution of sample means?
the sample means will form a normal distribution because the parent population is normal
A new instructional method is found to increase average exam grades from 80.20 to 80.21. That's not much of a change, but it was found to be statistically significant. How could that happen.
the sample size was very large
a new instructional method is found to increase average exam grades from 80.20 to 80.21. That's not much of a change, but it was found to be statistically significant. How could that happen?
the sample size was very large
A z score of 3 or higher indicates
the score is far from the mean
Which of the following is true of scatterplots?
the scores for one variable are on the x axis and the scores for a second variable are the y axis
In a frequency distribution graph, the horizontal axis shows
the scores for the variable
If Group 1 in your study has a standard deviation of 10 and Group 2 in your study has a standard deviation of 5, then you know that
the scores in Group 1 are more spread out than the scores in Group 2
All other things being equal, the larger your sample size (n)...
the smaller the standard error of the mean
all other things being equal, the larger your sample size (n)...
the smaller the standard error of the mean
The standard error of the sample mean is
the standard deviation of the distribution of sample means
Cohen's d measures effect size in what units?
the standard deviation of the variable
As the sample size becomes very large
the standard error becomes very small
What happens to the standard error of the mean when the sample size increases?
the standard error decreases
If the standard deviation of a dataset is 9, what is the variance?
81
Which set of scores has the least variability?
91, 92, 93, 94
for Cohen's d, which of the following would be considered a moderate effect size?
0.51
In a normal distribution, the probability of selecting a score that is between 1 standard deviation below and 1 standard deviaion above the mean would be
0.6826
In a normal distritbution, the probability of selecting a score that is between 1 standard deviation below and 1 standard deviaion above the mean would be
0.6826
A normal distribution has a mean of = 60 with = 8. What is the probability of selecting an individual with a score greater than 54?
0.7734
A researcher concludes that a new treatment works significantly better than an existing treatment for improving depression. However, this finding is just unique to the specific sample and does not reflect what would happen in the population. This is an example of...
A&B are correct
a researcher concludes that a new treatment works significantly better than an existing treatment for improving depression. However, this finding is just unique to the specific sample and does not reflect what would happen in the population. This is an example of...
A&B are correct
If the standard error of the mean (SE) for a sample is 5 points, then..
Both A and B are correct
If the standard error of the mean (SE) for a sample is 5 points, then... - The sample may have overestimated the population mean by 5 points - The sample mean may have underestimated the population mean by 5 points - Both A and B are correct - None of the other options are correct
Both A and B are correct
Why do many researchers prefer the experimental method of research?
Both a and b
As sample size increases, the standard error of the mean
decreases
Inferential statistics are used to do what?
determine whether the patterns between variables are reliable and not due to sampling error
Which of the following is true of scatterplots?
each single point shows one participant's scores on two variables at once
You conduct a study to compare the mean GPA of male college students to the mean GPA of female college students. You find that the 90% confidence interval for the difference between the two means is -0.45 to +0.56. The best interpretation of this confidence interval is that
You are fairly confident that there is no significant difference in GPAs between male and female college students
Which of the following studies would best be analyzed with an independent samples t-test?
You randomly assign children with a diagnosis of ADHD to two different treatment groups and then compare the two groups on their academic success in class for the a month
Suppose you find out that your z-score on an exam is +3.00. Which of the following is true?
Your score was higher than most of the other student's scores
Which of the following is NOT a reason why being able to calculate Z-scores is considered important?
Z-scores change ordinal scales to ratio scales
Which confidence interval would lead one to NOT reject the null hypothesis that the population mean is zero? (Assume that the probability of a Type I error is set at 5%).
a 95% confidence interval from -2 to 5
How will a weak positive correlation look on a scatterplot?
a loosely grouped pattern that is lower on the left side of the scatterplot and higher on the right
All other things being equal, in which scenario, would the p value for the independent-samples t-test most likely be less than .05?
a mean difference of 6 points and an n (sample size) of 60
What is a sample mean often treated as an estimate of?
a population mean
A doctor collect data from his patients on whether or not they are a smoker to see how it predicts their health. In this example, whether or not someone is a smoker is
a quasi-independent variable
A researcher is interested in testing whether introverts (shy people) or extraverts (outgoing people) have better short-term memory. Introversion/Extraversion is
a quasi-independent variable
For a research study comparing attitude scores for males and females, participant gender is an example of what kind of variable?
a quasi-independent variable
How will a perfect negative correlation appear on a scatterplot?
a straight line that slopes downward
A z-score for an x score tells you
all of the above
Which statement is true?
as sample size increases, power increases
Dr. Lashun finds amount of sleep and reaction time are correlated at r = -.28. Which of the following best describes this relationship?
as sleep increases, reaction time tends to decrease
Dr. Lashun finds words typed per minute and reading comprehension are correlated at r = .45. Which of the following best describes this relationship?
as words typed per minute decreases, reading comprehension tends to decrease
which of the following is appropriate for graphing continuous data?
either a histogram or frequency polygon
If you calculate the 95% confidence interval for a sample mean, you know that
in repeated sampling, the true population mean would fall in the given interval 95% of the time
What is one way to decrease the standard error of the mean?
increase the sample size
what is one way to decrease the standard error of the mean
increase the sample size
The type of treatment used in a research study describes the
independent variable
The term "inferential" in inferential statistics is appropriate because we
infer about the characteristics of a population based only on a sample
Hypothesis testing is a(n)
inferential method for determining whether a population parameter has a particular value
Most often, when you arrive at a conclusion about your study's hypothesis, the last step in the statistical analysis requires
inferential statistics
Which of the following pairs of variables should produce a negative relationship (correlation)?
number of hours studying and number of errors on a math exam
An example of a variable measured on a ratio scale is
number of random acts of kindness observed
Which of the following is an example of a discrete variable?
number of stoplights in a city
Which of the following sample means will have the largest standard error (sampling error)?
one where the sample size is 100 and the population standard deviation is 10
If you scored at the 90th percentile on a test, you would know that
only 10% of the students who took the test scored higher than you
The standard error is used instead of the standard deviation when examining
sample means rather than individual scores
In a hypothesis test, the critical region consists of
sample values that are very unlikely to be obtained if the null hypothesis is true
Dr. Spearmint conducts a study where she changes the room temperature and measures its effect on participant's performance on a simple task. What is his dependent variable?
task performance
Which of the following is most likely a continuous variable?
temperature in degrees celsius
Inferential statistics are most commonly used to do what?
test a hypothesis
A researcher is interested in the political orientation of UCA students. He distributes a social conservatism survey to 50 students. What is the sample?
the 50 students
What is wrong with the following report of a Pearson r correlation coefficient: r (25) = 0.00, p < .05.
the Pearson r value of zero cannot have a probability value <.05
Which of the following is an example of a continuous variable?
the amount of time it takes to solve a problem
Suppose a research report indicates that their sample of 100 females had the following statistics regarding IQ scores: M = 110, SE = 1.5. Which of the following is the correct interpretation of these statistics?
the average IQ score for the sample was 110 and that sample mean is most likely off by 1.5 points from the true population mean
Standard deviation is best conceptualized as
the average distance of scores from the mean
A standard deviation is conceptually most similar to what?
the average of all deviations from the mean
a standard deviation is conceptually most similar to what?
the average of all deviations from the mean
If a researcher conducts both a one-tailed and two-tailed hypothesis test, both with an alpha of .05, which is true of the two tests' critical regions?
the critical region is the same size in both tests
the denominator of an independent-samples t-test represents which of the following?
the difference between the two sample means you can expect to get by chance
as sample size increases, what happens to the mean and standard error of a sampling distribution?
the mean stays the same and the standard error decreases
On a boxplot, the heavy line near the middle of the box represents
the median value
Which of the following is least likely to be found if a sample is randomly drawn from a population?
the sample mean is 2.5 standard errors from the population mean
a two-sample t-test results in n obtained value for t of zero. when will this happen?
the two samples has the same mean
A two-sample t-test results in an obtained value for t of zero. When will this happen?
the two samples have the same mean
When is is the mean considered LEAST useful as a measure of central tendency?
when the distribution is very skewed or contains extreme outliers
Under what circumstances would a score that is 15 points above the mean be considered to be near the center of the distribution?
when the population standard deviation is much larger than 15
When is the mode the only measure of central tendency that can be used?
when the variable is nominal or categorical
When would you expect the standard error of the mean to increase?
when variability in a population is higher
A doctor collects data from his patients on whether or not they are a smoker. In this example, what is/are the variable(s)?
whether or not someone is a smoker
A researcher gives 10 people a strong cup of coffee, and another 10 a cup of decaf. He then measures their heart rate. What is the independent variable?
whether or not the people drank regular or decaf caffeine
Under what circumstances is the median likely to produce a better measure of central tendency than the mean??
with an extremely skewed distribution
If the value of zero does NOT fall within your confidence interval for a two-sample test,
you are fairly confident that there is a significant difference between your means
you just completed a study in which you concluded that female students had significantly higher GPAs than male students. It is possible that
you are making a Type 1 error
You just completed a study in which you concluded no significant difference in introversion personality scores between greek and non-greek students. It is possible that
you are making a Type II error
If the t-value for your independent samples t-test has a p (probability) value less than your alpha level, then
you should reject the null hypothesis and conclude that the two group means are significantly different
What is the median for the following set of score: 1, 3, 3, 5, 6, 7, 8, 9, 10
6
A very bright student is described as having an IQ that is three standard deviations above the mean. If this student's IQ is reported as a z-score, the z-score would be __________.
+3
Over a number of days, you measure the outside temperature with two thermometers, one that provides the temperature in degrees Celsius and the other that provides the temperature in degrees Fareinheit. The correlation between the readings from the two thermometers would be
1
For a normal distribution, what score cuts the distribution into 50% above and 50% below
A & B are correct
Which of the following is true?
A and B are correct
Which of the following is true? - Descriptive statistics can be performed without inferential statistics - Inferential statistics often involve first calculating descriptive statistics - A and B are correct - none of the other options are correct
A and B are correct
Which of the following is true of scatterplots?
An inverse (negative) relationship is represented by a slanted line that goes from the upper left corner of the graph down to the bottom corner of the graph
You conduct a study to investigate the possible relationship between number of pets someone has and diastolic blood pressure. The results are as follows: r(70) = -.25, p = .03. Which of the following is the correct interpretation of the p value?
Assuming there is NO relationship between number of pets owned and diastolic blood pressure, you would obtain the r of .25 or more extreme 3% of the time due to random sampling error.
Which of the following is true about the difference between interval and ratio scales?
Interval scales may have a score of 0, but (unlike with ratio scales), it does not represent the true absence of what is measured.
Which of the following is NOT a reason why scatterplots are useful?
None of the other answer is correct - all are reasons that scatterplots are useful
Suppose a researcher tests whether males or females have higher scores on a standard extraversion scale. Which of the following statement correctly descibes the difference between the p and a confidence interval for this scenario?
P value will tell you if there is likely a difference between the males and females, the confidence interval will give you estimate of the range of possible values for the difference
A perfect positive correlation would be represented by
Points that form a completely straight line that goes from the bottom left corner of the graph up to the top right corner of the graph
Descriptive statistics can describe the characteristics of a _________ while inferential statistics draw inferences about the characteristics of a __________
Sample; population
Suppose you have a score of 80 on a math exam for which the class average was 70 and the standard deviation 10. Suppose you have a score of 70 on an Spanish exam for which the class average was 50 and the standard deviation 8. For which class did you have the highest score relative to the rest of the students in the class?
The Spanish class
If all the possible random samples of size = 30 are selected from a population of scores that is positively skewed with a µ = 80 and a δ = 10 and the mean is computed for each sample, then what shape is expected for the distribution of sample means?
The sample means will form a normal distribution because the sample sizes are relatively large
If group 1 in your study has a standard deviation of 10 and Group 2 in your study has a standard deviation of 5, then you know that
The scores in Group 1 are more spread out than the scores in Group 2
Dr. Vation tests 50 students' short-term memory. He finds one student has a Z-score of -1.5. What does this tell him about the student's memory?
Their memory score is 1.5 standard deviations below the mean memory score
Dr. Stake concludes that morning statistics classes don't differ from afternoon classes in average grade. However, there actually is a difference at the population level. What kind of error has she made?
Type II error
A z-score of z = -2.00 indicates a position in a distribution __________.
below the mean by a distance equal to 2 standard deviations
An advantage of experimental research over correlational research is
clearer statements of causality can be made
Which dataset would be most appropriate to use a histogram to graph?
graduates from a psychology program by year
Confidence intervals are most often used as
an inferential statistic to supplement null hypothesis testing
Which statistic does not belong with the others?
mean
On a boxplot, the distance between the ends of the box represents
the interquartile range
For a sample of college students, you measure both the amount of time each day that a person spends on social media and that person's GPA. The scatterplot for these data, with social media time on the x-axis and GPA on the y-axis, indicates a tightly grouped oval of points that is higher on the left side of the graph and lower on the right side of the graph. Your best guess at to the Pearson r correlation coefficient value for these data would be r =
-0.8
Which of the following sets of correlations correctly shows the highest to lowest strength of relationship?
-0.91, +0.83, +0.10, -0.03
A researcher determines that students study an average of 80+/-20 (M+/-SD or Mean plus or minus Standard Deviation) minutes per week. Assuming these data are normally distributed, what is the z score for students studying 60 minutes per week?
-1
When low scores on one variable occur with high scores on another, and vice versa, their correlation coefficient will be somewhere between________ and ________
-1 and 0
For a population with a mean of µ = 80 and a standard deviation of δ = 10, what is the z-score corresponding to X = 70?
-1.00
A set of 30 exam scores with a mean of 60 and a standard deviation of 5 is converted to z-scores. What will be the mean of the transformed scores?
0
A population has µ = 50 and δ = 10. If these scores are transformed into z-scores, the population of z-scores will have a mean of __________ and a standard deviation of __________.
0 and 1
When high scores on one variable occur with high scores on another, and low scores occur with low scores, their correlation coefficient will be somewhere between________ and ________
0 and 1
R-squared as a measure of effect size will always have a value in the range _________ and indicates the ________.
0-1; proportion of variance accounted for
a treatment is administered to a sample selected for a population with a mean of = 80 and a standard deviation of = 10. After treatment, the sample mean is M=85. Based on this information, the effect size as measured by Cohen's d is
0.05
A sample of 16 scores provides a mean of 12 and a standard deviation of 8. If the null hypothesis states that the population mean is 10, what is the value of Cohen's d?
0.25
For a population with µ = 100 and δ = 20, what is the X value (raw score) corresponding to z = 2.00?
140
Which set of scores has the least amount of variability?
145, 143, 145, 147
which set of scores has the least amount variability
145, 143, 145, 147
Suppose the correlation between height and weight for adults is +0.40. What percent of the variability in weight can be explained by the linear relationship between height and weight?
16%
An introductory psychology class has 9 freshman males, 15 freshman females, 8 sophomore males, and 12 sophomore females. What is the probability of randomly selecting a male from this class?
17/44
An introductory psychology class has 9 freshman males, 15 freshman females, 8 sophomore males, and 12 sophomore females. What is the probability of randomly selecting a male from this group?
17/44
A statistics exam has an average score of 75, with a standard deviation of 4. If a student scores an 83 on the exam, what is their z score?
2
You have a distribution of scores such that Q1 =10, Q2 = 20, and Q3 = 30. The interquartile range (IQR) would be
20
A population of N = 10 scores has mean = 50 and standard deviation = 5. What is the population variance?
25
Each quartile of a distribution of scores contains ______ of all the scores.
25%
What percentage of scores in a distribution are between the third and fourth quartile?
25%
Which set of scores has the greatest amount of variability?
27, 105, 10, 80
What is the mode for the following set of score: 3, 3, 1, 5, 8, 7, 6, 9, 10
3
Scores on the Math Achievement Test form a normal distribution with a mean of µ = 300 and a standard deviation of δ = 100. What score separates the top 50% of the distribution from the rest?
300
A population of N = 10 scores has a mean of µ = 50 and a standard deviation of δ = 6. What is the population variance?
36
If the variance of a dataset is 16, what is the standard deviation?
4
A population of N = 8 scores has EX = 40. What is the population mean?
5
A set of scores from a sample has a variance of 25, what would the standard deviation be?
5
Identify the median of the following set of scores: 2, 2, 3, 4, 5, 6, 6, 9, 9
5
A student takes a personality test, which gives them Z-scores for 5 different personality traits, all of which are normally distributed. Their Z-score for extraversion is a -2.0. If the mean extraversion score on the test is a 60 with a standard deviation of 5, what was the student's extraversion score?
50
The range for the scores (4, 6, 2, 8) is what?
6
Which of the following statements CANNOT be true for a distribution of scores?
60% of the scores are above the median
which confidence interval would lead one to NOT reject the null hypothesis that the population mean is zero? (Assume that the probability of a type 1 error is set at 5%).
a 95% confidence interval from -2 to 5
Any time a researcher conducts a study and uses inferential statistics, it is possible they will
all of the above are true
An independent samples t-test is appropriate for what type of research design?
a between-participants design
an independent samples t-test is appropriate for what type of research design?
a between-participants design
A good analogy for a type II error is...
a blood test incorrectly indicating that a person does not have Lycanthrophy
A good analogy for a type 1 error is...
a blood test incorrectly indicating that a person has Lycanthropy
A good analogy for a type I error is...
a blood test incorrectly indicating that a person has Lycanthropy
You measure a person's shoe size and their GPA and find no significant relationship between these two variables. Your best guess as to the visual pattern of points on the scatterplot would be
a circle of points without any obvious tilt to them
Professor Sample wants to know if people's age is related to their short-term memory. This question is best answered by:
a correlational study
If rejecting the null is thought of as a "positive" test result and failing to reject it a "negative", a Type 2 error could also be called:
a false negative
If rejecting the null is thought of as a "positive" test result and failing to reject it a "negative", a Type II error could also be called:
a false negative
if rejecting the null is though of as a "positive" test result and failing to reject it a "negative", a Type 2 error could also be called
a false negative
If rejecting the null is thought of as a "positive" test result and failing to reject it a "negative", a Type I error could also be called:
a false positive
How will a strong negative correlation look on a scatterplot?
a tightly grouped pattern that is higher on the left side of the scatterplot and lower on the right
A researcher concludes that people who prefer dogs have significantly higher IQ's than those who prefer cats. However, this finding is just unique to the specific sample and does not reflect what would happen in the population. This is an example of...
a type 1 error
Increasing the alpha level (for example from = .01 to = .05)
all of the above are true
If you scored at the 80th percentile on a test, you would know that
all of the other answers are correct
What is the advantage of correlational research designs?
all of the above
A vertical line is drawn through a normal distribution at z = 1.00. The line separates the distribution into two sections and the larger section corresponds to __________ of the whole distribution.
about 84%
a vertical line is drawn through a normal distribution at z=1.00. The line separates the distribution into two sections and the larger section corresponds to _______ of the whole distribution
about 84%
An instructor examines the scores on her first exam, which has a typical scale of 1 to 100 and a fairly normal distribution. Which measure of central tendency is appropriate for this variable.
all of the above
Dependent variables
are measured for possible changes
A graph repesenting the number of majors in each department within the College of Health and Behavioral Sciences would be a
bar graph
A physical therapist measures how many times participants can lift a 40 lb weight. What should she use to graph her data?
bar graph
The frequencies of ordinal and norminal variables are best represented by...
bar graph
You decide to record the academic major for each student in an introductory psychology class. If the data are presented in a frequency distribution graph, what type of graph should be used?
bar graph
What is the biggest advantage of the research design referred to as naturalistic observation?
behavior is usually more natural
A statistics instructor pulls out 10 of her students' exams from a pile of 50 to start grading. Because the suspense is killing her, she calculates the mean exam score for these 10 students to get a better idea of how the whole class might do. The instructor has used
both descriptive and inferential statistics
If a researcher wants to use data from a sample to draw conclusions about a population, they would need to use
both descriptive and inferential statistics
If a distribution has two scores that are tied for most common, which is the mode?
both scores are the mode
You conduct a study and find a negative correlation between a child's relationship with their teacher and the number of disciplinary referrals to the principal's office. The most appropriate conclusion is that
children with better teacher relationships also tend to have fewer disciplinary referrals
The Yerkes-Dodson law states that moderate levels of physiological arousal are related to optimal performance. Arousal levels higher or lower than this optimal level produce poorer performance. Given this, you would expect Person r to be
close to zero
An example of a variable measured on an ordinal scale is
college classification (freshman, sophomore, etc.)
which of the following research situations would be most likely to use a quasi-experimental design with different people in different groups
compare the mathematics skill for 9th-grade boys versus 9th-grade girls
Which of the following research situations would be most likely to use a quasi-experimental design with different people in different groups?
compare the mathematics skills for 9t-graders boys versus 9th-grade girls
Variables can be __________, but measurements are always __________
continuous, discrete
As a measure of how much knowledge of psychology students have gained during the semester, an instructor gives a 50-item multiple choice exam. "Knowledge" is an example of what type of variable?
continuous, quantitative
To assess students' interest in class lectures, an instructor tracks daily attendance. "Interest" would be an example of what type of variable?
continuous, quantitative
as a measure of how much knowledge of psychology students have gained during the semester, an instructor gives a 50-item multiple choice exam. "Knowledge" is an example of what type of variable?
continuous, quantitative
A researcher has participants rate their overall happiness on scale of 1(extremely unhappy) to 10(extremely happy) to see how this relates to their GPA. We would describe the underlying variable of happiness as ___________ and the specific way that we are measuring it as ____________.
continuous; discrete
Other things held constant, as you increase sample size, the shape of the sampling distribution of the mean will
decrease
Many majors (like psychology) have "category requirements" for elective classes. For example, Theories of Learning (PSYC 3351) and Cognitive Psychology (PSYC 3325) are labeled "Category II." Health Psychology (PSYC 3305) and Sports Psychology (PSYC 3370) are labeled "Category IV". The category to which a course belongs is what type of variable?
discrete, qualitative
Cause/effect questions are the type of questions used by which method of research?
experimental
Suppose a researcher tests whether males or females have higher scores on a standard extraversion scale and on a standard depression scale. For extraversion, they obtain the following 95% confidence interval[2, 5]. For depression, the obtain the following 95% confidence interval [1, 6]. For which scenario did we obtain a more precise estimate?
extaversion
suppose a researcher tests whether males or females have higher scores on a standard extraversion scale and on a standard depression scale. For extraversion, they obtain the following 95% confidence interval [2,5]. For depression, they obtain the following 95% confidence interval [1, 6]. For which scenario did we obtain a more precise estimate?
extraversion
A Type I error means that a researcher has
falsely concluded that a treatment has an effect
A Type II error means that a researcher has
falsely concluded that a treatment has no effect
a type 2 error means that a researcher has
falsely concluded that a treatment has no effect
For the past 20 years, the high temperature on April 15th has averaged 62 degrees with a standard deviation of 6 degrees. Last year, the high temperature was 74 degrees. Based on this information, last year's temperature on April 15th was __________.
far above average
For the past 20 years, the high temperature on April 15th has averaged = 62 degrees with a standard deviation of = 2. Last year, the high temperature was 68 degrees. Based on this information, last year's temperature on April 15th was
far above average
A list of all possible values of a variable and the number of times each value occurs is called a
frequency distribution
A group of researchers thought that the amount of time alloted to take a quiz would cause changes in students' frustration levels. What was their dependent variable?
frustration levels
Which of the following variables would most likely result in a positively skewed distribution of scores?
home prices in Little Rock, AR
When reporting household incomes for a geographical region (i.e., city, state, nation), the median is preferred over the mean. This is because
household incomes likely represent a skewed distribution
A frequency distribution shows
how many individuals scored a particular score for a variable that you measured
Testing hypotheses is generally done through some form of __________
inferential statistics
What term is used to denote statistical procedures that use sample data to make conclusions about the larger population from which the sample was obtained?
inferential statistics
testing hypothesis is generally done through some form of _______
inferential statistics
Variability which is defined as difference between third and first quartile is considered as
interquartile range
What scale of measurement are most psychological variables (e.g., depression, anxiety, mood, attitude) assumed to follow?
interval
What scale of measurement is used for quantitative variables, but has an arbitrary zero point?
interval
In a non-normal distribution, the probability of selecting a score that is above two standard deviations from the mean is...
it is impossible to tell
Which of these is the correct interpretation of the p value?
it shows the probability that you would have obtained the sample statistic's value or more extreme if the null were true
The larger the population standard deviation, the _____ the standard error of the mean will be.
larger
The larger the level of confidence, the ______ precise the interval estimate.
less
the larger the level of confidence, the _______ precise the interval estimate
less
If there is less variability of scores in your population, then you would expect
less sampling error
What proportion of a normal distribution is located in the tail beyond z = 2.00?
less than 5%
The variability of the sample means in a sampling distribution will always be
less than the variability of scores in the population
In an experiment, the independent variable is _______ by the experimenter
manipulated
The measure of central tendency that is obtained by adding all of the observed scores and dividing by the number of those scores is the
mean
If you have a score of X = 75 on an exam, which set of parameters would give you the highest position within the class relative to the other students?
mean = 60 and standard deviation = 5
For a perfectly symmetrical normal distribution, which relationship is always true?
mean = median = mode
A researcher reports that the size of an effect in some population is d = 0.88. Which of the following is an appropriate interpretation for d?
mean scores shifted 0.88 standard deviations in the population
When you do a correlational study, you, as the researcher
measure two variables but do not manipulate (control) either one
Which of the following is most likely a variable measured on a ratio scale?
minutes to complete a race
which of the following is most likely a variable measured on a ratio scale?
minutes to complete a race
The measure of central tendency that indicates which value of a variable occurs most often is the
mode
If there is greater variability of scores in your population, then you would expect
more sampling error
As the standard error of the mean goes up, individual means will be
more spread out around the population mean
A vertical line is drawn through a normal distribution at z = 1.00. The line separates the distribution into two sections and the larger section corresponds to __________ of the whole distribution.
more than 75%
To get a more precise estimate of a population parameter from a confidence interval, you would need a _________ interval, providing _________ confidence.
narrow, weaker
A researcher records the odometer reading and price for a group of used Hondas. What kind of correlation is likely to be obtained for these two variables?
negative
Dr. Stake concludes that students who study more get higher average statistics grades than students who study less, and there actually is a difference at the population level. What kind of error has she made?
no error has been made
The course numbers for 2000-level courses (for example, MATH 2331, PSYC 2330, or PSYC 2370) are examples of which scale of measurement?
nominal
Whether or not someone is in the experimental group or the control group in a study represents which scale of measurement?
nominal
Whether or not someone is married represents which scale of measurement?
nominal
Bar graphs are used to represent the frequency for which type of variables?
nominal and ordinal
What population parameters must be known to run an independent samples t-test?
none of the above
Which of the following is true of a normal distribution?
none of the other options are correct
A researcher selects two samples of 25 participants each. In the first sample the population mean was 32 and the variance was 8. In this second sample, the population mean was 4 and the variance was 8. Which sample will be associated with a larger standard error of the mean?
none, both samples will have the same value for standard error
A researcher reports a Pearson r of -2.10. What does this tell you about the relationship between two variables?
nothing other than that the researcher made an error
Measures of effect size are important statistics because
null hypothesis testing only allows you to conclude whether or not there is a significant effect - not how large the effect is
Measures of effet size are important statistics because
null hypothesis testing only allows you to conclude whether or not there is a significant effect - not how large the effect is
Which of the following is an example of a discrete variable?
number of children in a family
An example of a variable measured on a nominal scale is
number on an athletic jersey
Conceptually, the standard error of the mean tells you
on average, how far off your samples means are likely to be from the true population mean
Using inferential statistics to arrive at conclusions about behavior means that
one makes a decision based on the probability that differences or relationships between variables exist in those not even tested as part of a study
A statistics instructor calculates the standard deviation (how different scores are from each other) for a set of homework scores to see how much scores tend to differ. The instructor has used
only descriptive statistics
If a researcher is only interested in the data they've collected and not estimating any unmeasured scores, they would need to use
only descriptive statistics
A person's class rank amongst their high school class is an example of which scale of measurement?
ordinal
As a measure of how much knowledge of psychology students have gained during the semester, an instructor gives a 50-item multiple choice exam. The test grade (A, B, C, D, F) is an example of which scale of measurement?
ordinal
Determining the class standing (1st, 2nd, and so on) for the graduating seniors at a high school would involve measurement on a(n) _____ scale of measurement.?
ordinal
Interstates running from West to East have even numbers, with lower numbers in the South and higher numbers in the North. For example, I-40 runs through Arkansas, I-80 through Illinois, and I-90 through New York. This numbering system is an example of what scale of measurement?
ordinal
Dr. Coral measures a sample's self-esteem and their level of openness to new experiences. She finds that people with higher self-esteem scores tend to have higher openness scores, and vice versa. Self-esteem and openness are probably ___________
positively correlated
A population of scores has a mean of mean = 26, median = 23, and mode = 22. What is the most likely shape for the population distribution?
positively skewed
Reaction time is a commonly used variable in psychological research. Reaction times are usually close to the minimum possible time but sometimes take considerably longer. Distributions of reaction times are most likely:
positively skewed
The power of a statistical test is best described as the
probability of finding a significant effect/relationship when one in fact exists in the population
An advantage of the stem-and-leaf display over a histogram is that it
provides the original individual values
An instructor randomly assigns some of her classes to engage in a 3 minute mindfulness breathing activity before a quiz and others classes to engage in a 3 minute break before a quiz. She compares their quiz scores to see which group performed better. What is the dependent variable?
quiz scores
an instructor randomly assigns some of her classes to engage in a 3 minute mindfulness breathing activity before a quiz and others classes to engage in a 3 minute break before a quiz. She compares their quiz scores to see which group performed better. What is the dependent variable?
quiz scores
The most powerful way to create the groups for an independent samples t-test is to
randomly assign participants to two different groups
Sir Francis Galton created a graph where the heights of parents were represented on the X-axis and the heights of their adult children on the Y-axis. Thus, each point on the graph represented a pair of parent/child heights. This type of graph is called a
scatterplot
In a normal distribution, what scores have the highest probability of being randomly drawn?
scores that are closer to the mean
Which of the following can correlations NOT be used to do?
show cause and effect between two variables
Dr. Spearmint conducts a study where she changes the size of written text and measures its effect on participant's reading comprehension. What is the independent variable?
size of text
What kind of distribution shape can NOT be symmetrical?
skewed
Which of the following does not belong with the others?
skewed
Which of the following does not belong with the others? - bell-shaped - symmetric - uniform/rectangular - skewed
skewed
Based on the effect size conventions, d = 0.18 is a
small effect size
based on the effect size conventions, d=0.18 is a
small effect size
On an exam with a normal distribution and a population mean of 30, you have a score of 35. Which value for the standard deviation would give you the highest position in the class distribution?
standard deviation = 2
The standard error of the mean (SE) is like the
standard deviation for the sampling distribution of means
The standard deviation for the distribution of sample means is called the
standard error
A number that describes how likely your sample mean will be close to the true population mean is the
standard error of the mean
The best measure of sampling error is the
standard error of the mean
The measure of variability on a sampling distribution of the mean is the
standard error of the mean
Which of the following is NOT a measure of effect size?
t score
which of the following is NOT a measure of effect size?
t score
A researcher is interested in the political orientation of UCA students. He distributes a social conservatism survey to 50 students. What is the relevant statistic?
the average opinion of the 50 students
You determine that the variance for the CLASS SIZE variable is 64. This tells you that
the average squared distance of class size scores from the mean is 64 students
Which of the following is true when you increase the sample size for a study?
the likelihood of rejecting the null increases and there is little to no effort on the effect size
The denominator of an independent-samples t-test represents which of the following?
the difference between the two sample means you can expect to get by chance
The numerator of an independent-samples t-test represents which of the following?
the difference in the two sample means observed in the study
the numerator of an independent-samples t-test represents which of the following?
the difference in the two sample means observed in the study
A veterinarian collects information about the weight of her clients' dogs, cats, gerbils, and hampsters. For which group is the standard deviation for weight probably larger?
the dogs
A predicted effect is tested by a null significance hypothesis test, and a statistically significant result is found. Which of the following describes the most appropriate conclusion to take from the test:
the effect is likely but not certain to exist in the population
A null hypothesis is most likely to be rejected when
the effect size is large, but there is little variability in the scores
A researcher increases his level of confidence from 90% to 95%. What will happen to the precision of his estimate?
the estimate will be less precise
a researcher increases his level of confidence from 90% to 95%. What will happen to the precision of his estimate?
the estimate will be less precise
In a frequency distribution graph, the vertical axis shows
the frequency
A recent study reports that students who just finished playing a prosocial video game were more likely to help others than students who had played a neutral game. For this study, what is the dependent variable?
the helping behavior of the students
What is the main difference between an independent samples t-test and a single sample t-test?
the independent samples test uses sample means to estimate both population means
The correct interpretation of a 95% confidence interval is that
the interval has a 95% chance of including the population mean
A recent study reports that students who just finished playing a prosocial video game were more likely to help others than students who had played a neutral game. For this study, what is the independent variable??
the kind of game given to the students
All other things being equal (e.g., sample size, etc), which of the following is true?
the larger the absolute value of your test statistic, the smaller your p value
The higher the confidence interval (e.g., 95% vs 90%)
the larger the range of values as estimates of the population
which of the following is true when you increase the sample size for a study?
the likelihood of rejecting the null increases and there is little to no effect on the effect size
A researcher is interested in the impact of natural surroundings on brainstorming. She randomly assigns some invidviduals to brainstorm as many uses of a brick as they can imagine while sitting in a garden and others to do the same brainstorming task while sitting in a cubicle. The independent variable is
the location of the brainstorming task
When randomly drawing scores from a normal distribution, the farther a score is from the mean...
the lower the probability of finding it
The higher that a score is in a distribution of scores
the lower the probability of randomly selecting such a score
What information can measures of effect size give us that hypothesis testing alone does not?
the magnitude of the difference between populations
The weights of male and female students in a class are summarized in the boxplots below. Which of the following statements is NOT true?
the male students' weights have less variability than the female students' weights
Which of the following is an example of a descriptive statistic?
the mean of a sample of test scores
The expected value of the sample mean is
the mean of the distribution of sample means
What is are confidence intervals most often used to estimate?
the mean of the population
The midpoint of a confidence interval is always
the mean of the sample (single sample study) or the mean difference in the samples (two-group study)
As sample size increases, what happens to the mean and standard error of a sampling distribution?
the mean stays the same and the standard error decreases
You determine that the interquartile range (IQR) for the CLASS SIZE variable is 15 units. This tells you that
the middle 50% of class sizes range over 15 units
A set of students is surveyed about their major, what is the best measure of central tendency for this variable?
the mode
a set of students is surveyed about their major, what is the best measure of central tendency for this variable?
the mode
A therapist is investigating the impact of a new treatment for depression compared to an old treatment. Which of the following accurately representes the null hypothesis.
the new treatment produces results that are the similar to the old treatment
A therapist is investigating the impact of a new treatment for depression compared to an old treatment. Which of the following accurately represents the null hypothesis.
the new treatment produces results that are the similar to the old treatment
In a frequency distribution for a person's age, the height of the bar or curved line represents
the number of people of a particular age
A researcher collects information from all the first year high school teachers in a given city about the subject they teach, their gender, and their age. Which of the following would definitely be a constant (not a variable) in their data?
the number of years they have been teaching
If a 95% confidence interval for a two-sample test does not contain 0...
the p value for the test statistic will be less than .05
If a person has a Z-score of exactly 0, what does that indicate?
the person's score is exactly the same as the mean score
if a person has a Z-score of exactly 0, what does that indicate?
the person's score is exactly the same as the mean score
What would be a reasonable null hypothesis for a two-sample t-test?
the population means are the same
what would be a reasonable null hypothesis for a two-sample t-test
the population means are the same
If each sample includes only 1 score, the standard error of the sample means would be
the population standard deviation
The alpha level determines
the probability of a Type 1 error
For a normal distribution with mean = 60 and standard deviaton = 8, the probability of selecting a score greater than X = 64 is equal to
the proportion of the distribution with z-scores greater than 0.50
For a normal distribution with µ = 60 with δ = 8, the probability of selecting a score greater than X = 64 is equal to __________.
the proportion of the distribution with z-scores greater than 0.50
A problem with using the mode as a measure of central tendency is that
the same set of data can produce more than one mode
When a random sample is selected from a population, the sample mean is not expected to be exactly equal to the population mean. On average, the size of the difference between the sample mean and the population mean is predicted by
the standard error of the mean
Which of the following defines the expected difference between a population's mean and the mean of a sample randomly drawn from it?
the standard error of the mean
The statistical output for an independent samples t-test shows t(32) = 1.26, p = .50. This output indicates that
the study had 34 participants and you should conclude that the two groups are NOT significantly different
You conduct a study to investigate the possible relationship between number of pets someone has and diastolic blood pressure. The results are as follows: r(70) = -.25, p = .03. Which of the following is the correct interpretation of the results?
the study showed that owning more pets is associated with lower blood pressure
The heigth of each bar on a frequency histogram represents
the total number of participants who scored that particular score
the height of each bar on a frequency histogram represents
the total number of participants who scored that particular score
If you sum up the frequency values in a frequency distribution, that number will tell you
the total number of scores in your sample
A researcher shows that a new treatment significantly reduces depression, with an r-squared of .25. What is the correct interpretation of this value?
the treatment accounted for 25% of the variance in depression
The mean of the sampling distribution of the mean is always equal to
the true population mean (or your best estimate of it)
What would be a reasonable alternative hypothesis for a two-sample t-test?
the two population means are different
what would be a reasonable alternative hypothesis for a two-sample t-test?
the two population means are different
When the null hypothesis is rejected in an independent samples t-test, what conclusion is being drawn?
the two populations being compared probably have different means
Which of the following could be a null hypothesis of a two-tailed hypothesis test?
the two populations have the same mean
A researcher believes that powdered unicorn horn improves memory. To test this, the researcher has participants study a list of 20 words. Prior to this, the researcher sprinkles half of the participants on the head with powdered unicorn horn and the other half with baby powder. What is the independent variable in this study?
the type of powder
The standard error of the mean best describes
the variability of sample means
Which of these statements is NOT true of a sampling distribution? - it's a distribution of a very high or infinite number of sample means - with a large enough sample size it always follows a normal distribution - the mean of the sampling distribution is the same as the population mean - the variability of the sampling distribution is the same as the variability of a distribution of individual scores from the same population
the variability of the sampling distribution is the same as the variability of a distribution of individual scores from the same population
A histogram would be used instead of a bar graph if ________
the variable is continuous
a histogram would be used instead of a bar graph if ________
the variable is continuous
For a sample of college students, you measure both the amount of time each day that a person spends on social media and that person's GPA. The scatterplot for these data, with social media time on the x-axis and GPA on the y-axis, indicates a tightly grouped oval of points that is higher on the left side of the graph and lower on the right side of the graph. Your interpretation of this scatterplot would be
there is a strong negative correlation between social media time and GPA
For an independent samples t-test, the null hypothesis states that
there is no difference between the two population means
The null hypothesis for a one-sample test states
there is no difference between the two population means
the null hypothesis for a one-sample tests states
there is no difference between the two population means
the null hypothesis for one-sample test states
there is no difference between the two population means
Which of the following is true?
there may be a causal relationship, but a correlational design can not establish a casual relationship
A researcher conducts a study in which one group of students receives encouraging words before a test and a control group receives no encouraging words. She examines the impact of this on test scores. The results are as follows: t(40) = 3.00, p = .004. What is the most appropriate conclusion given an alpha level of .05?
there was a significant difference in test scores between the groups
Suppose a researcher tests whether married versus single people have higher scores on a standard extraversion scale and on a standard depression scale. For extraversion, they obtain the following 95% confidence interval [1, 5]. For depression, they obtain the following 95% confidence interval [-5, 5]. Which of the following statements is true?
there was not a significant difference between married and single people for depression, but there was for extraversion
If the same data is displayed in a frequency polygon (line graph) and a bar graph, how will the shapes of the two graphs differ?
there will be no difference in shape
Suppose a researcher collects the degrees in Celcius and Farenheit in Conway over a month. Which of the following statements is most correct?
there would be a perfect positive correlation
Which of the following describes why confidence intervals are often useful?
they provide a range of estimated values for the population mean rather than a single number
which of the following describes why confidence intervals are often useful?
they provide a range of estimated values for the population mean rather than a single number
You conduct a study to investigate the possible relationship between the number of bystanders around a victim that needs help and the time it takes for someone to provide help. The result of your Pearson correlation coefficient analysis showed r (46) = +0.15, p = +0.08. The most appropriate conclusion would be that
this study showed no significant relationship between the number of bystanders and time to provide help
A population distribution has µ = 80 and δ = 6. In this distribution a z-score of z = +2.00 identifies a location __________.
twelve points above the mean
Inferential statistics are estimates of unknown information, so they always involve some degree of _________
uncertainty
The owner of Betty's Machetes conducts a survey with a sample of 25 of her customers to see the mean (average) satisfaction rating for their last machete purchased. If she wants to see if she can generalize the results to the larger population of customers, she should
use both descriptive and inferential statistics
If you choose a sample at random from a population, it will most likely be
very close to the population mean
if you choose a sample at random from a population, it will most likely be
very close to the population mean
When we use inferential statistics to arrive at a conclusion in our study
we are confident of our conclusion but realize that we are not 100% sure
Which of the following is a continuous variable?
weight
In which of the following scenarios would the assumption of homogeneity of variance be violated.
when one group has a narrow distribution of scores and the other group has a very wide distribution of scores
When would you be least likely to need inferential statistics?
when you are only interested in the scores you've measured
when would you be least likely to need inferential statistics?
when you are only interested in the scores you've measured when you're trying to predict future scores
The interquartile range for a set of scores tells you
where the middle 50% of the scores lie around the median
You just completed a study in which you concluded that female students had significantly higher GPAs than male students. It is possible that
you are making a Type I error
which of the following studies would best be analyzed with an independent samples t-test?
you randomly assign children with a diagnosis of ADHD to two different treatment groups and then compare the two groups on their academic success in class for a month
if the t-value for your independent samples t-test has a p (probability) value less than your alpha level, then
you should reject the null hypothesis and conclude that the two group means are significantly different
For a normal distribution, what z-score value separates the lowest 10% of the distribution from the highest 90%?
z = -1.28
For a normal population with a standard deviation of 20, what is the z-score corresponding to a score that is 10 points below the mean?
z =-.50
If you have a score of X = 75 on an exam, which set of parameters (mean = µ and standard deviation = δ) would give you the lowest position within the class?
µ = 70 and δ = 10