PSY 200 Final exam
Which of the following values of the correlation coefficient (r) indicates the weakest relationship between two variables?
+0.25
A perfect correlation will result in a coefficient value of:
-1.00 or +1.00
The critical value(s) associated with a p level of 0.05 for a one-tailed hypothesis test using the z statistic is/are:
-1.65, 1.65
The critical value(s) associated with a p level of 0.05 for a two-tailed hypothesis test using the z statistic is/are:
-1.96 and 1.96
A researcher collect 15 data points that yield a mean of 9.164 and a standard deviation (based on N - 1) of 2.377. If the researcher is comparing the sample to a population mean of 10.6, what is the value of the test statistic?
-2.339
Assume the cholesterol levels in a certain population have mean µ= 200 and standard deviation σ = 24. The cholesterol levels for a random sample of n = 9 individuals are measured and the sample mean x is determined. What is the z-score for a sample mean x = 180?
-2.50
The critical value(s) associated with a p level of 0.01 for a two-tailed hypothesis test using the z statistic is/are:
-2.58, 2.58
A researcher measures the following data: 3,3,3,4,4, and 4. What is the population variance for these data?
.25
If the p level is 0.05 and the null hypothesis is true, what is the probability of making a Type I error (i.e. that one will fail to reject the null hypothesis)?
0.05
A researcher measures the following data: 3,3,3,4,4, and 4. What is the sample variance for these data?
0.3
Suppose the correlation coefficient between height (as measured in feet) versus weight (as measured in pounds) is 0.40. What is the correlation coefficient of height measured in inches versus weight measured in ounces? [12 inches = one foot; 16 ounces = one pound]
0.40
For a random sample of 9 women, the average resting pulse rate is x = 76 beats per minute, and the sample standard deviation is s = 5. The standard error of the sample mean is
1.667
An instructor give students a surprise quiz and records a mean grade of 12 points. What is the new mean value if the instructor adds 10 points to each quiz?
22
An instructor give students a surprise quiz and records a mean grade of 12 points. What is the new mean value if the instructor doubles each quiz score?
24
Thomas decides to use the mode as a measure of central tendency for his map study. What is the mode in the data set: 13, 27, 22, 15, 14, 26, 27, 22, 17, 27, 15, 13?
27
In order to assess the effect of pet ownership health, a researcher surveys 150 people who own pets and 150 people who do not own pets. The sample being studied is:
300 people
For the scores: 9,8,4,2,3,6, the median is:
5
If the correlation coefficient is 0.8, the percentage of variation in the response variable explained by the variation in the explanatory variable is
64%
A researcher records the number of time that 10 students cough during final exam. He records the following data; 0, 0, 0, 3, 3, 5, 5, 7, 8, and 11. Will the range be smaller than the interquartile range?
7, 7, 8, 10, 10
A clinical researcher is interested in testing the effectiveness of a new drug on depression. She gives a paper survey to 10 clients about their current level of depression, then prescribes the new drug for 6 months. After this time, she gives the same survey to the same clients to see if their levels of depression got better or worse. What statistical test is she most likely to run for this experiment?
A paired-samples t test
In which situation would it be necessary to use a between-groups ANOVA?
A researcher is interested in the effects of distraction on driving performance and randomly assigns participants to one of three distraction groups.
Given a scale dependent variable and a nominal independent variable with three or more levels, a(n) ___ could be used to analyze the data.
ANOVA
Which of the following will decrease the value of the mean
Add a score below the mean
Which of the following has no effect on the mean?
Add a score exactly equal to the mean
Which of the following will decrease the median?
Adding score below the median
A psychologist wants to study a small population of 40 students in a local private school. If the researcher was interested in selection the entire population of students for this study, then how many student smust the psychologists include?
All 40 students, because all students constitute the population
Researchers who study the process of reading in children have discovered that better readers make smoother eye movements across the page (e.g. there is a positive correlation between reading skill and the smoothness of the eye movements). Which of the following is a possible cause of this correlation?
All of these options are possible causes of the correlation
The following data set is 16,17,20,20,20,26,29,29,30,30,30,31,31,56
Bimodal
The type of car you drive is what type of variable?
Categorical
A four-year college wants students to live on campus during their first and second year. In a class of 18 students, the professor does a quick check to see the distribution of students across those two living options. What statistical test could be used to analyze these data?
Chi-square test for goodness of fit
What is the best way to test if males and females differ in their propensity to be either a Democrat or a Republican?
Chi-square test for independence
The strength (degree) of the correlation between a set of independent variables X and a dependent variable Y is measured by
Coefficient of Correlation
The percent of total variation of the dependent variable Y explained by the set of independent variables X is measured by
Coefficient of Determination
Which of the following will increase the value of the mean?
Delete a score below the mean
Which branch of statistics uses numerical observations and incorporates them into an organized and informative summary of the data?
Descriptive
________________________ are procedures used to summarize, organize and make sense of scores called data.
Descriptive statistics
True or False; A scientist measures the following data: 21,23,24,26,31 and 32. The value for the sample variance and population variance will be the same?
False
Pulse rates of adult men are approximately normal with a mean of 70 and a standard deviation of 8. Which choice correctly describes how to find the proportion of men that have a pulse rate greater than 78?
Find the area to the right of z =1 under a standard normal curve.
The mean is a preferred descriptive statistic;
For describing symmetrical (normal) distributions
Why is it sometimes easier to use a frequency table to interpret data than to examine a distribution of raw scores?
Frequency tables display patterns, organizing the data based on how often each score occurs.
What type of graph would be appropriate to display the number of televisions owned by a sample of 100 people?
Histogram or frequency polygon
In comparing frequency tables with grouped frequency tables for the same set of data, which of the following would be true?
If the dataset is large, the grouped frequency table would be easier to read.
Imagine you collected eye color data for 500 people. When creating a frequency distribution, would you use a grouped frequency or an individual frequency?
Individual, because the number of possible eye colors is limited.
________________________ uses probability to determine how confident we can be that our conclusions are correct.
Inferential statistics
_________________________ uses probability to determine how confident we can be that our conclusions are correct.
Inferential statistics
What is the primary limitation of the correlation coefficient?
It cannot be used to establish causal relations between two variables
What is the formula for computing the range?
Largest value minus the smallest value
The _______________________ is the preferred measure of central tendency when a data set has outliers.
Median
A researcher is interested in the number of books owned by middle school children living in poverty in the United States. He randomly selects 2000 children to survey. What is the population?
Middle school children living in poverty in the United States
When scores on a variable are demonstrated by a histogram, and the majority of the scores are concentrated around high scores on the variable, the best way to describe the distribution of scores is as a
Negative Skew
A researcher reports that participants in her study had a mean age of 21.3, with a rage equal to 3. Based on the information, is it possible that one of the participants was 25 years old in her study?
No the range is too small
The number of children per household according to the U.S. Census would be which type of variable?
Numerical
____________________ describe(s) characteristics in a population whereas ________________________ describe(s) characteristics in a sample.
Parameters; statistics
College students at 20 campuses were polled to find out how many students owned iPhones. All college students would be an example of
Population
When scores on a variable are demonstrated by a histogram, and the majority of scores are concentrated around low scores on the variable, the best way to describe the distribution of scores is a
Positive Skew
In a journal article, standard deviation is abbreviated as:
SD
A group of researchers measures the weight of five participants prior to a clinical weight loss intervention. They record the following weights (in pounds) 200, 250, 150,100 and 300. The median is 200. The researcher realize that the scale was not accurate for the individual weighing 300 pounds, so they reweigh that individual and recorded 250. Will the median
Stay the same
R2 is the mathematical notation for:
The Co-efficient of Determination
A deviation is:
The amount that a score in a sample deviates from the mean.
Relationship between correlation coefficient and coefficient of determination is that
The coefficient of determination is the coefficient of correlation squared
When looking at a distribution of scores that is skewed, what is the best measure of central tendency to use?
The median, because it is less affected by skewness.
A result is called "statistically significant" whenever
The p-value is less or equal to the significance level
in Statistical testing of hypothesis, what happens to the region of rejection when the level of significance is reduced?
The rejection region in reduced in size
In the Zimbardo prison study, students were assigned to be either a prisoner or a guard so that the experimenters could examine prison life behaviors and interactions. However, the study had to end early because students assigned to the prisoner role were suffering from psychological breakdowns. What was the independent variable in this study?
The role of prisoner or guard.
An instructor measures the following quiz scores:6, 8, 7 and 9 (SD = 1.29). If the instructor subtracts 2 points from each quiz score, how will the value of the standard deviation change?
The standard deviation will not change (SD = 1.29)
Which of the following is NOT true about the standard error of a statistic?
The standard error increases as the sample size(s) increases
True or False; A scientist measures the following data: 23,23,23,23,23 and 23. The value for the sample variance and population variance will be the same?
True
True or false; when all scores in a population are the same, the variance will always be equal to 0.
True
The average squared deviation from the population mean is the _____________________
Variance
In testing the statistical hypothesis, which of the following statements is false?
When testing for a directional hypothesis (one tailed) the critical region is two sided
Which of the following refers to a single score in a distribution of scores?
X
When conducting a paired-samples t test, one can assess the research hypothesis and get a range of mean differences that could be expected in the future using:
a confidence interval
Kurtosis defines peakiness of curve in the region which is
around the mode
Twenge and Im (2007) found that between 1958 and 2001, the need for social approval of people n the U.S. was negatively correlated with the U.S. divorce rate during that same time period (r = -0.38). This means that:
as the need for social approval increased, divorce rates decreased
In a symmetrical distribution, third quartile and first quartile of data in distribution must
be at equal distance
An independent-samples t test a ___ design.
between-groups
If the coefficient of determination is equal to 1, then the correlation coefficient
can be either -1 or +1
If the coefficient of determination is 0.81, the correlation coefficient
could be either + 0.9 or - 0.9
If the coefficient of determination is a positive value, then the regression equation
could have either a positive or a negative slope
If you add all the previous relative frequencies to the relative frequency of the current row you would get a _________________.
cumulative frequency
n-1 is the
degrees of freedom (df)
A psychologists is interested in the influence of sleep loss on working memory. He tests subjects at 8 AM after a full night's sleep, then tests them the following day after being awake all night. What statistical analysis should be performed to answer this question?
dependent-samples t test
College students at 20 campuses were polled to find out how many owned iPhones. The number of owners on one campus would be an example of a(n) ______ statistic.
descriptive
What is the correct formula for calculating a probability
divide number of successes by number of trials
Creating a _____ table involves summarizing a group of data by listing each possible value along with how frequently the value occured
frequency
The chi-square test for ___ is appropriate when there is one nominal variable while the chi-square test for ___ is appropriate when there are two nominal variables.
goodness of fit; independence
The correlation of height and weight is 0.75, and the correlation of depression and satisfaction with work is -0.42. Which is a stronger correlation and why?
height and weight: 0.75 is closer to 1 than -0.42 is to -1.
If a negative relation exists between two variables, then low scores on one variable will be associated with ___ scores on the other variable
high
Increasing sample size:
increases the likelihood that we will reject the null hypothesis
A group of rats ran faster with a steroid drug supplement compared to a group of rats that received no drug. Which type of statistical test should be used to report these results?
independent-samples t test
In a(n) ___, two distinct groups are used to compare the distribution of mean difference scores.
independent-samples t test
The ___ can be thought of as the range of the middle 50% of the data.
interquartile range
A confidence interval is a(n) ___ that includes the population mean after repeatedly sampling
interval estimate
The coefficient of correlation
is the square root of the coefficient of determination
A term meaning how flat or tall a data set is refers to ________________.
kurtosis
In a distribution that is positively skewed, most of the scores occur on the ____ of the distribution.
left side
A negatively skewed distribution has a long tail to the ___ of the distribution, and a positively skewed distribution has a long tail to the ____ of the distribution.
left; right
Scatterplots visually depict the type of relation between two variables, such as a ___ relation where the data fall along a straight line and a ___ relation, where the data follow a curved or broken pattern.
linear; nonlinear
Obtaining a measure of intelligence from a group of college students would likely yield a somewhat normal distribution (that is, there are probably no outliers). What would be the best measure of central tendency to use in this example?
mean
Outliers have the greatest effect on the:
mean
Considering mean, mode and skewness of data, value of skewness will be negative if
mean < mode
After grading exams, Sylvia realizes that the distribution of scores is positively skewed. Which measure of central tendency should she use for this data?
median
A researcher was interested in assessing whether a new medication had negative side effects on reaction time. He performed an experiment on a group of rats. One group of rats received the medication and the other group of rats did not. The researcher then measured reaction time differences between the two groups on a series of tasks. In this experiment, the independent variable is:
medication
The regression line is the line that:
minimizes our error in predicting scores on the dependent variable
It is possible for a distribution to have more than one:
mode
Professor Taylor recently administered a psychology exam and was surprised to see that the distribution of scores was positively skewed. For this example, a positively skewed distribution indicates:
most students did poorly on the exam, but a few did very well.
To predict a single dependent variable from more than one independent variable, which statistical technique would you use?
multiple regression
As the age of a male professor increases, the hair on his head decreases. This is an example of what type of correlation?
negative
What kind of correlation would you expect to find between the severity of snowstorms and rates of attendance at college classes?
negative
A distribution containing a few very small values is likely to create a distribution that is:
negatively skewed
If we asked 100 people how much they like pizza, we would probably find that most people like it a lot but some people like it only a little or not at all. This would most likely be a ____ distribution.
negatively skewed
Twenty people participate in a weight-loss program for two months. Their weights after the two months are compared to their starting weights. What kind of mean difference might be expected if the null hypothesis is true for a paired-samples t test?
no change in weight or weight gain, indicating that the program does not work.
A frequency distribution that is bell-shaped, symmetric, and unimodal is called a _____ distribution
normal
If we created a frequency polygon of sample data and noticed that most of the scores fell in the middle of the distribution with smaller numbers in either tail, we would probably call this a ____ distribution.
normal
The form of the alternative hypothesis can be:
one or two-tailed
If a teacher is trying to prove that new method of teaching math is more effective than traditional one, he/she will conduct a
one-tailed test
A positive correlation between hand size and foot size indicates that
people with larger feet also tend to have larger hands
What kind of correlation would you expect to find between levels of family income and educational level?
positive
Identify the shape of the following scores: 1, 1, 2, 3, 3, 3, 4, 5, 7, 10, 19, 40.
positively skewed
Simple linear regression allows us to:
predict an individual's score on the dependent variable from their score on the independent variable
Regression is a type of statistical analysis that is most useful for:
predicting behavior
Regression is to ___ as correlation is to ___.
prediction; relation
When data are divided into four equal parts, the data are split into ________________.
quartiles
Which of the following values could not represent a correlation coefficient?
r = 1.09
The coefficient of determination is the
ratio of the explained variation to the total variation.
Data that have not been transformed or analyzed are referred to as:
raw scores
A researcher was interested in assessing whether a new medication had negative side effects on reaction time. He performed an experiment on a group of rats. One group of rats received the medication, while the other group did not. He then measured reaction time differences between the two groups on a series of tasks. The dependent variable is:
reaction time
An insurance company hires Ulrich to explain car accidents that are the result of people who look at the road while driving but do not see an oncoming car, a type of accident labeled as "driver looked but did not see." Ulrich creates an experiment in which participants see two pictures flashing on a computer screen. Both pictures show the same scene but one is slightly different. Ulrich records how long it takes people to notice the change (reaction time) and how many sets of pictures they correctly find the difference within the 5 minute time set. What should Ulrich include on a scatterplot to most effectively describe these data?
reaction time and number of correct differences identified
The ratio (fraction or proportion) of the number of items a value of the data occurs in the set of all outcomes to the total number of outcomes is ___________.
relative frequency
The phrase "statistically significant" means that the:
research result was unlikely to have occurred by chance.
A two-tailed test is one where:
results in either of two directions can lead to rejection of the null hypothesis
It becomes progressively easier to declare statistical significance as the ___ increases.
sample size
S2 is equal to
sample variance
The line of best fit, which is used to make predictions for y variables on the basis of values of x, is constructed using a:
scatterplot
What type of graph would be appropriate if you would like to display the relation between two scale variables?
scatterplot or line graph
An important point to remember about correlation is that while there is a ___ relationship, correlation does not equal ___.
statistical; causation
Numbers based on samples are referred to as ___ while numbers based on populations are referred to as ___.
statistics; parameters
The correlation coefficient is how one measures the ___ of a correlation
strength
Identify the shape of the distribution of the following scores: 1, 2, 2, 3, 4, 4, 5.
symmetrical
The interquartile range is a measure of the distance between:
the 25th percentile and the 75th percentile of a data set.
Smaller p-values indicate more evidence in support of:
the alternative hypothesis
Psychologists studying infant memory want to determine at what age babies can remember specific events. An experimenter uses several puppets to demonstrate a series of actions while the infant watches. After a delay, the experimenter records how many of the actions the child imitates when playing. The dependent variable is
the amount of imitated actions
"The incidence of depression among college students is negatively correlated with the number of sunny days each year in the locale where they attend college." This statement means that:
the chances of a college student being depressed tend to increase as there are fewer sunny days
How does calculation the sample variance differ form calculating the population variance?
the denominator is n-1 rather than n
In computing variance and standard deviation, we are interested in how much individual scores vary from:
the mean
The statement "On average, older adults have the same response time as younger adults" is an example of:
the null hypothesis
Chi-square tests assess whether:
the observed data differ from the pattern expected given the null hypothesis
A negative correlation between a hockey player's age and the number of minutes he spends in the penalty box indicates that:
the older a player is, the less time he tends to spend in the penalty box.
When one refers to "how significant" the sample evidence is, he/she is referring to the:
the p-value
If all the points on a scatterplot fall on a single line:
the relation between the variables is perfect
If the points on a scatterplot are all close to the regression line:
the standard error of the estimate is small
The symbol N represents:
the total number of scores in a sample.
If two variables, x and y, have a very strong linear relationship, then
there might not be any causal relationship between x and y
Sophia is interested in measuring whether there is a difference between time spent sleeping for elementary-school aged children and high-school aged children in a given week. The dependent variable is most likely:
time spent sleeping
Frequency distribution is considered as positively skewed if all the values of the distribution moves to the
upper tail
As compared to measures of variation, measure of skewness is used to understand concentration of
values around mean
When creating histograms and frequency polygons , the x-axis typically represents ______ and the y-axis typically represents _____.
values or intervals; frequencies
How "spread out" a group of scores is, refers to _______________.
variability
Hypothesis testing tells
what results are significant, but no details regarding significant results.
Hypothesis testing tells:
what results are significant, but no details regarding significant results.
Suppose that vehicle speeds at an interstate location have a normal distribution with a mean equal to 70 mph and standard deviation equal to 8 mph. What is the z-score for a speed of 64 mph?
−0.75
