Psych 302 Final
Which of the measures of central tendency always changes if one score changes
mean
What are the measures of central tendency?
mean, median, mode
What value is obtained if you sum all the squared deviation scores from a population and then divide that sum by N
population variance
The probability of rejecting a null hypothesis that is false is called
power
By following two groups of people, one who smokes and one who doesn't, the researcher is engaging in ---- research.
quasi- experimental, non- experimental
What kind of measurement scale is necessary to be able to meaningfully say that one score is twice as large as another
ratio
If a teacher gives everyone a grade based on the month they were born, this would be a ----- measure of how well students did in the course
reliable, but not valid reliability= repeatability. stating that everyone born in January will get an A is very reliable. Validity= correctness. The month of birth is not an accurate measure of someone's coursework
According to the Cohen's rule-of-thumb interpretation of r-values, an r of .75 would be considered a ____________ correlation.
strong
Correlation measures ---- of a relationship between two continuous variables.
the direction and strength
An interaction between factor A and factor B occurs when the effect of factor A is different depending on
the level of factor B
If the data set is skewed what is true?
the mean and the median will be different values
The grand mean is
the mean of all observations across groups
Another term for the independent variable is
the predictor variable
Eta squared indicates the percentage of:
variance in a dependent variable
The degrees of freedom for a χ 2 test of independence is equal to...
(number of rows-1) x (number of columns -1)
----- statistics describe the data from our sample. ----- statistics use sample data to estimate characteristics of the population.
Descriptive; interval
What is the effect of decreasing the alpha level?
Increase the likelihood of Type II error Decrease the likelihood of rejecting the null hypothesis
Studying the relationship between geographical location and political views, a researcher compared scores on the conservative values questionnaire among samples from New York, South Carolina, Kansas, Montana and Oregon. What in this scenario would be referred to as a level? questionnaire score
New York, South Carolina, Kansas, Montana or Oregon
Which variable should you plot on the x-axis?
The casual variable, if one exists.
When will the independent samples t- value be more likely significant?
When there is a small variability within each group When the differences between samples means are large
Given the following regression equation, interpret the y- interpret the y- intercept. Y i ^ = 23.44 − 2.66 Xi
When x= 0, y is expected to be 23.44 units
Given no other information, is the sample mean an unbiased estimate of the population mean?
Yes
What are two examples of a quasi independent variable?
Younger and older adults are compared in terms of their crystalized intelligence Depression rates are compared between men and women
A correlation coefficient r = 1 indicates
a perfect positive relationship
A developmental psychologist is interested in whether 2-year-olds have a preference among the three primary colors: red, blue, and yellow. He samples n= 70 2-year-olds, has each child pick her/his favorite color, and records the choices. Which test?
chi- square goodness of fit: equal proportions
An eta squared value of 0 indicates
no effect of group
A study comparing Oregonians and Washingtonians on their tolerance to kombucha drinking reported t(26)=1.66, p > 0.05. What was the sample size?
28
In a 3 X 2 X 2 factorial ANOVA design, output from the analysis will include _______ main effects.
3
Given a normal distribution, what is the percentage of cases between the mean and -1 standard deviation?
34.1 34.1% of cases fall between mean and 1SD from the mean
Suppose a researcher is interested in whether there is a relationship between amount of caffeine consumed and the number of words recalled from a list. Which test?
Correlation
A researcher reports that people need eight hours of sleep to function efficiently during the day. In her review she states that 70% of the American population gets less than eight hours of sleep a night, 20% gets eight hours, and 10% gets more than eight hours. You survey 100 college students and find 80% get less than eight hours of sleep a night, 15% get eight hours, and 5% get more than eight hours. How do college students' sleep patterns compare to the general public? Which of the following is the appropriate null hypothesis?
H0: P = (.7, .2, .1)
A political analyst is interested in how urban, suburban, and rural voters differ in exposure to political campaign ads. They measure the number of minutes per week spent watching public television.
One- way between subjects ANOVA
Which of these observed values are more likely to lead to rejecting of the null hypothesis
a very small p- value a large F- value
In a χ 2test of independence, the __________ hypothesis states that the probabilities of one variable do not depend on the value of another variable.
alternative
The difference between the formula for the one- sample t- test statistic and the z- test statistic is that the one sample t stat uses
an estimated standard error
Which of the following statements are true regarding hypothesis testing?
as power increases, the probability of incorrectly retaining a null hypothesis decreases as effect size increases, the power to detect an effect increases In hypothesis testing, the sampling distribution is used to determine how likely our test statistic is assuming the null hypothesis is true
When you run an ANOVA with more than two-groups and end up with a significant result, what can you conclude?
at least one population mean is different from at least one other population mean
Most researchers report the standard deviation as the prime measure of variability. This is because it can be interpreted in terms of the ----- units, unlike variance.
average
In a factorial ANOVA analysis, variability due to row, column, and interaction effects is considered ------- groups variability
between
One way to think about the F- value in ANOVA is as a ratio comparing variability due to treatment and variability due to error. The variability due to treatment in this calculation refers to the
between group variance
Under what circumstances will be the F- statistic the largest?
big differences between means, large sample size
Under what circumstances will be the absolute value of the t- statistic the largest?
big differences between means, large samples size
A researcher wants to compare males and females on smoking behavior. Smoking is measured as a nominal variable (smoker, nonsmoker, former smoker).
chi- square test of independence
In a one-way, repeated-measures ANOVA, the degrees of freedom associated with variability due to individual differences are called
dfSubjects
When do we need to conduct post- hoc tests after running a factorial ANOVA?
if we find a significant main effect of a factor that has 3 or more levels
A statistics professor is interested in the effect of electronic textbooks on learning. She assigns one of her sections of introductory statistics to use a traditional textbook and the other section an equivalent electronic textbook. One question the professor might ask is whether the choice of textbooks had an effect on exam performance. Which statistical test would be the most appropriate choice to investigate this question?
independent samples t- test
What statistical test should be used to compare psychology knowledge of students who are psychology majors with those who are not
independent samples t- test
A researcher believes that recall of verbal material differs with the level of processing. He divided his subjects into three groups. In the low processing group, participants read each word and were instructed to count the number of letters in the word. In the medium processing group, participants were asked to read each word and think of a word that rhymed. In the high processing group, participants were asked to read each word and think about something that happened to them that would relate to that word. Each group was allowed to read the list of 30 words three times, then they were asked to recall as many of the words on the list as possible. If the researcher wants to know whether the three groups have different amounts of recall, what type of statistical test should be used?
one- way between subjects ANOVA
A researcher wants to know if class (freshman, sophomore, junior, senior) is associated with number of parties a student attends each term. Which statistical test you would use to answer the research question and/or analyze the data described?
one- way between subjects ANOVA
A psychologist is interested in attitudes towards the disabled. She believes that contact with someone who is disabled might have an effect on peoples' attitudes. To test her hypothesis, she measured attitudes toward the disabled both before and after contact with an individual in a wheelchair. What type of statistical test should she use to determine if contact with a disabled person changes peoples' attitudes toward the disabled?
paired samples t- test
A demographer hypothesized that men and women in a heterosexual relationship differential support same sex marriages. He randomly sampled 250 heterosexual couples and asked each wife and each husband to indicate their support for the same- sex marriages on a 10- point scale. Which test should a demographer use.
paired t- test
The mean of the distribution of sample means is equal to the ----. The standard deviation of the distribution of sample means is called the -----.
population mean; standard error
A Web developer believes that the amount of time individuals spend on a particular Web page is drastically affected by the types of images that are displayed on that page. In order to show her customers that this is the case, she creates three Web sites that are identical except for the images displayed: one has images of kittens, one has images of landscapes, and one has images of happy couples. She invites 25 participants into her office and asks each participant to browse all three Web sites. For each participant, she records the amount of time that the individual spent at each site. Which test would she most likely use to find out if the type of images affects browsing time?
repeated measures ANOVA
A summer camp director wanted to find out if campers' degree of homesickness changed over time. She took a sample of them at her camp, and at three timepoints -- beginning, middle and end of the camp -- asked them to fill out the interval-scale Homesickness Inventory. What statistical test should she choose to analyze her data?
repeated measures ANOVA
Description of Type II error:
retaining a false null hypothesis
The standard deviation can be stated as:
the square root of the variance the average distance from the mean in standard units
You ran a pre-post study design, measuring reaction times in a simple detection task before and after drinking a cup of coffee. In order to calculate the standard error of the difference scores for a paired samples t-test, you need to know
the standard deviation of the difference scores the sample size
The results of a t- test depends on the sample size. What happens as you increase sample size?
the standard error decreases the critical value of t decreases
The standard error for an independent samples t- test represents
the standard error of the difference between sample means
What does it mean that a t- test is statistically significant
the t- statistics has a p- value lower than the alpha
The probability of retaining the null hypothesis when it is false is called __________
type II error
A t- distribution with which of the following degrees of freedom most closely resembles the standard normal distribution?
40
On average, what value is expected for the z- statistic when the null hypothesis is true?
0
The most commonly used measure of effect size for an independent samples t- test is
Cohen's d
Why is variance value less useful for describing variability of data compared to standard deviation?
It is in squared units It cannot be interpreted in terms of the original variable.
Which of the following statements about a χ 2goodness-of-fit test are TRUE?
It is used for nominal variables It compares the observed number of observations in a group to the expected number of observations
Researchers want to know if people in Oregon spend more time outdoors than people in the US in general. They collect a sample of Oregonians and ask them how many hours per week they typically spend outdoors. Which of the following statistical tests would be appropriate for this analysis?
One sample t test
A researcher investigated the relationship between personality type and risky behavior. She gave personality inventories to 100 high school students and asked each one if he or she had ever driven drunk. She found that out of 60 extroverts, 45 had driven drunk. Out of 40 introverts, only 10 had driven drunk. Which of the following is the appropriate alternative hypothesis?
P(extrovert and has driven drunk) ≠ P(introvert and has driven drunk) P(extrovert and has not driven drunk) ≠ P(introvert and has not driven drunk)
The results of a factorial ANOVA are reported as follows: For the main effect of Factor A, F(1,25) = 5.36, p < .05. For the main effect of Factor B, F(1,25) = 2.23, p > .05. For the interaction, F(1,25) = 1.32, p > .05. Given this report, which of the following is true?
Retain the null hypothesis for the interaction and one main effect. Reject the null hypothesis for the effect of Factor A.
Which variable should you plot on the y- axis?
The effect (outcome) variable, if there is one.
A waiter wants to know whether it is true that leaving a small chocolate with the bill will increase tips and whether the chocolate has a different influence on men than it does on women. If the waiter asked me to design an experiment to test this, what type of statistical test will I be planning on performing?
factorial ANOVA
A study design with more than one grouping variable is called...
factorial design
The t- distribution, especially at lower level of degrees of freedom, has ----- than the normal distribution
fatter tails
When should researchers use the mode?
for nominal data
A good regression line....
goes right through the middle of h
Larger F- values indicate that
group mean differences are larger than what would be expected by chance there is greater variability between groups than within groups the observed data are unlikely if the null hypothesis was true
A psychologist is interested in whether or not handedness is related to gender. Specifically she wants to know if the percentage left-handed men in the population is different from the percentage of left-handed women. She collected data on handedness for 200 men and 200 women. What type of statistical test would be appropriate?
chi- square test of independence
Charlotte has been dating her new partner, Anna, for one month, and she thinks the relationship is going extremely well. Being a curious scientist, Charlotte wants to know whether there is a relation between her mood and the numbers of hours she spends in a day with Anna. Charlotte has been recording her daily moods (for another project) on a 1 to 10 scale (10 indicates extremely happy) and she is also keeping a diary so she can look up how many hours each day in the last months she spent with Anna. Which test?
correlation
To study the relationship between memory and age, professor Zeithamova collected a large sample of participants between ages 18-80 and administered them a word list learning task. The age of each participant and the number of words recalled from the list were recorded.
correlation
A one- way, between subjects ANOVA with two groups is the same as
independent samples t- test
A researcher wants to compare males and females on smoking behavior. Smoking is measured as the number of cigarettes smoked each day. Which statistical test you would use to answer the research question and/or analyze the data described?
independent samples t- test
Rejecting H0 when H0 is true is a __________ error. Retaining H0 when H0 is false is a __________ error.
type I error; type II
A researcher is running a one- sample, two- tailed t- test with an alpha level of .05. As the number of participants she collects increases, the critical t- value
decreases
As a sample size increases, standard error -----, because you sample estimate are closer to the actual population value.
decreases
In a one-way, repeated-measures ANOVA, the degrees of freedom associated with variability due to the independent variable are called _____.
dfTreatment
In ANOVA, what is the most commonly used measure of effect size?
eta squared
We can only run a chi-square test if the ____________ is at least 5.
expected frequency in each cell
A researcher is interested in the effects of personality and noise level on task performance. The researcher randomly selects introverts and extraverts for the personality variable. He places half of the participants in a quiet room, and the other half in a noisy room. He then measures how many errors participants make in the task. Which test?
factorial ANOVA
A researcher wants to know whether culture is related to the self-serving bias. She collects data from a group of U.S. students and a group of Chinese students. She has all participants complete a standard self-serving bias questionnaire (using a continuous scale), and tests which culture has a greater self-serving bias. Which test?
independent samples t- test
Children with autism experience difficulties understanding social affective cues, and it has been suggested that such deficits will generalize to music. In order to investigate this hypothesis, typically developing individuals and children with autism were asked to rate emotional qualities of music on a scale from 1 (sad) to 7 (happy)
independent samples t- test
A repeated measures ANOVA is usually more powerful than between subjects ANOVA because it can account for the variability in dependent variable that is due to
individual differences
The MS within is sometimes referred to as the error variance. A key source of error variance is
individual differences
Likert scales, such as "rate how outgoing you are on the scale from 1 to 5 are ordinal. But we treat them as
interval
Regression analysis found the best fitting line equation to be y_hat = 10 + 0.5*x What is the strength of the relationship between x and y?
it cannot be determined based on the regression equation alone
In a one way, repeated- measure ANOVA, which equation is used to calculate dfTreatment
k- 1
Which combination of factors will lead to the largest F- statistic
large differences among group means and small within- group variability
Which situation will lead to the largest F-statistic?
large differences among group means and small within-group variability
Which case will lead to the largest value for an F-statistic? _________ variability among sample means and _________ variability within each sample.
large; small
With a very small sample size, you would have a ---- standard error, which would yield a ---- confidence interval for the estimate
large; wide
A Pearson correlation coefficient measures the strength of the ________________ relationship between two variables.
linear
In a normal distribution, the value associated with the highest probability is equal to the
mean
You are analyzing a data set with multiple continuous predictors and one continuous outcome variable. Which statistical test should you use
multiple regression
In a one- way, repeated- measures ANOVA, which equation is used to calculate dfSubjects?
n- 1
Under which scenario will it be the most difficult to demonstrate differences between three groups using one-way, between-subjects ANOVA? Sigma denotes variability (standard deviation) within each population, n denotes sample size from each group.
n=10, sigma = 100
In a one- way ANOVA, the factor is most commonly on which type of scale?
nominal/ categorical
An untrue statement for a distribution of score:
none of the mode, median or mean can be above 60% of the scores
In a in one- way ANOVA, the outcome variable must be
on interval or ratio scale
Which inference test would we use for comparing conscientiousness score in a sample of UO undergraduates to the known national average
one sample t test
Principal Jones collects data on how students in her school performed on a standardized test that is measured on an interval scale. She wants to compare her school's performance to the mean of the rest of the schools in the state. She does not know the standard deviation of scores on this test for the state. Which statistical test you would use to answer the research question and/or analyze the data described?
one sample t- test
Survey data suggest that college students spend an average of 30 hours per week studying, with a standard deviation of 4 hours. You wonder if student athletes study the same amount. You survey 25 athletes and find that they study 25 hours per week. Which statistical test you would use to answer the research question and/or analyze the data described?
one sample z- test
A group of researchers is interested in knowing how love of coffee varies across different parts of the US. They obtain samples from Washington, Oregon, California, Illinois, and New York and have participants rate their love of coffee on a Likert scale from 1 to 7. Which of the following statistical tests would be appropriate for this analysis?
one- way between subjects ANOVA
When do we conduct post- hoc tests?
only after ANOVA results are significant
If the null is false (i.e., if there is a true effect in the population), what will happen in a statistical test of that effect if you increase the sample size?
p- value becomes smaller, effect size remains relatively unchanged, standard error becomes
A researcher hypothesizes that among twins, the twin who was born first is more extraverted. Which statistical test you would use to answer the research question and/or analyze the data described?
paired samples t test
You are interested to know if the number of syllables influences memory for words. You get 12 subjects and ask them to memorize 50 words. Twenty-five of the words are one-syllable words, and 25 are three-syllable words. You find that subjects remember an average of 15 of the single-syllable words and 8 of the three-syllable words. Which statistical test you would use to answer the research question and/or analyze the data described?
paired samples t- test
Researchers want to know if marionberry pie is better than regular blackberry pie. They recruit a sample of 50 participants and have them taste both pies and rate how delicious they are without the participants knowing which pie is which. Which of the following statistical tests would be appropriate for this analysis?
paired t- test
If the test statistic falls within the critical region, then we can
reject the null hypothesis
In t- tests, if the absolute value of the observed t- statistic is more extreme than the critical t, we ------ the null hypothesis and conclude that there ---- a significant difference.
reject; is
Chime wanted to know if students' sleeping habits vary over the semester. She surveyed 100 students and asked them to keep track of how many hours of sleep they got per night during the first two weeks of school, the two weeks before break, the two weeks after break, and during the last two weeks of school. Which statistical test you would use to answer the research question and/or analyze the data described?
repeated measures ANOVA
Stress decreases quality of sleep. This is an example of a ---- hypothesis.
research hypothesis
You are analyzing a data set with one continuous predictor and one continuous outcome variable. Which statistical test from the following list should you use? Correct Answer
simple regression
If the Pearson correlation coefficient is r = .9, then the slope in the regression equation will be
small or large, depending on the measurement units of the variable.
What is variance in terms of standard deviation?
standard deviation squared
You should use a one- way repeated measures ANOVA when
testing for significant differences between groups when the same participants are in each group
A factorial ANOVA should be used when:
the effects of two explanatory variables are being tested
The difference between simple and multiple regression is
the number of predictors
The probability of obtaining a test statistic at least as extreme as the one we did given the null hypothesis is known as..
the p- value
In a one - way ANOVA, the alternative hypothesis is that
the populations means are not all equal
In a normal distribution, the area under the curve refers to
the probability of obtaining a particular value
A one-way repeated measures ANOVA is used for experimental designs that collect data from...
the same participants in each condition
What does it mean when your observed sample mean falls within the critical region?
the sample mean is unlikely if the null is true the difference between the predicted and observed value is statistically significant
According to the central limit theorem, we can use sampling distributions to estimate population parameters because
the standard deviation of the sampling distribution can be calculated the shape of the sampling distribution becomes normal as sample size increaes the mean of the sampling distribution is the same as the mean of the population
To calculate eta squared, the ----- is divided by the sum of squares total.
the sum of squares between
Unlike one- sample z- test, one sample t- test can be used even when we do not know ----.
the value of the population standard deviation
According to the Cohen's rule-of-thumb interpretation of r-values, an r of -.3 is considered a ___________________ correlation.
weak
Under what circumstances is a score that is 2 points above the mean considered an extreme score?
when the population standard deviation is much smaller than 2
In an independent samples t- test, t- values can be positive or negative depending on
which group mean is subtracted from the other in the t- statistic formula
When would you use a one- sample t- test instead of a one- sample z- test?
you do not know the population standard deviation