PSY 302 final
The Director of Academic Support Services wanted to know if students with ADHD had more trouble with certain types of tests. A sample of 25 students with ADHD were given equivalent reading passage for each of three types of tests. Each student took a multiple-choice test, a fill-in-the-blank test, and a short essay test. Tests scores were compared for all conditions. What is the degrees of freedom for subjects in this scenario?
24
A researcher found a correlation between GPA and IQ scores of r = 0.32. What is the proportion of variance in the GPA explained by IQ? Round your answer to two decimal points.
0.1
A study reported a correlation between height and weight r = .5, p < 0.05. What is the proportion of variability in people's weight that can be explained by differences in height?
0.25
An analysis of student records found that 16% of variability in college GPA is explained by students high-school GPA. What is the correlation r between college GPA and high-school GPA?
0.4
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. What is the degrees of freedom for this test?
1
When the null hypothesis is true, the F-distribution tends to peak around
1
Under what circumstances will the distribution of sample means be a normal distribution?
When the population distribution is normal and/or when the sample size is large
Which of the following scenarios includes a quasi-independent variable?
Younger and older adults are compared in terms of their crystalized intelligence, Depression rates are compared between men and women
For a particular variable, Kana lists all the values in ascending order, then identifies the middle number, or the average of the 2 middle numbers. This results in a measure of ___________________ called the _____________.
central tendency; mean
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 independence
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 variable in this scenario would be referred to as a factor?
geographical location
A good regression line... (check all that apply)
has the smallest possible residuals, goes right through the middle of the data.
Eta squared is an effect size measure that refers to the proportion of variability _____________ that can be explained by the predictor.
in the outcome variable
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
Researchers wanted to compare the level of happiness in US, Finland, Brazil and South Africa. Which of the following statistical tests would be the most appropriate for this analysis?
one way anova
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 spend watching public television. What test would they employ?
one way, between subjects anova
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
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 spend watching public television. What test would they employ?
one-way between subjects 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
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
Listening to classical music while studying can improve test performance. This is an example of a __________ hypothesis.
research
If the null is true, any observed differences between the sample mean and the true mean are due to _________ .
sampling error
Taj is a 7th grader. Compared to her peers, Taj's height is at a z score of about z=2.3. What would we say about her height.
she is extremely tall
With a very large sample size, you would have a _____________ standard error, which would yield a ______________ confidence interval for the estimate.
small; narrow
If the population mean on a depression questionnaire is 7.1 and we draw a random sample from the population, which sample size will be more likely to produce a sample mean of 8.6 or larger?
smaller sample size
Unlike the standard deviation, variance is in terms of _____________ units and is _________________.
squared; difficult to interpret
When a random sample is selected from a population, the sample mean is not expected to be exactly equal to the population mean. What measure represents the typical size of the difference between a sample mean and the population mean?
standard error
According to the Cohen's rule-of-thumb interpretation of r-values, an r of .75 would be considered a ____________ correlation.
strong
A difference score is calculated by
subtracting the score that a participant obtained on the second variable from the score that the same participant obtained on the first variable.
The normal distribution is ____________, meaning that if you fold it in half vertically down the middle, both sides would be _______________.
symmetrical; identical
If we set 𝛼=.05α=.05, then which of the following is TRUE?
the critical region can only cover 5% of the sampling distribution, the probability of rejecting the null hypothesis when it is true is 5%
The 50th percentile is also known as
the median
In a one-way ANOVA, the between-groups degrees of freedom is equal to
the number of groups - 1
The difference between simple and multiple regression is
the number of predictors.
In a one-way ANOVA, the alternative hypothesis is that
the population means are not all equal
Another term for the independent variable is:
the predictor variable
Power refers to...
the probability of correctly rejecting the null hypothesis.
Given the results r(29) = -.84, p < .05, what are the most appropriate conclusions?
the results are statistically significant, X and Y have a negative relationship.
A one-way repeated measures ANOVA is used for experimental designs that collect data from...
the same participants in each condition
The standard error for an independent samples t-test represents ____________
the standard error of the difference between sample means.
What is the difference between a 𝜒2χ2 test of independence and a 𝜒2χ2 goodness-of-fit test?
the test of independence examines the relationship between two variables, while the goodness-of-fit test examines just one variable
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
In a one-way ANOVA, the null hypothesis is that...
there are no differences among any of the group means
In statistics, "N" refers to:
total # observations
This is an example of... false positive
type 1 error
The probability of retaining a null hypothesis that is false is called...
type II error.
Match the variable with its appropriate scale of measurement.
type of car: normal, order: ordinal, shoe size: interval, number of hairs: ratio
A researcher believes that the type of music someone listens to will cause someone to feel a certain way. In this example, the _______________ is the independent variable, and the _________________ is the dependent variable.
type of music; mood
Measuring someone's height based on number of stacked apples is ___________________.
valid but not reliable
The following equation refers to: ∑(𝑋−𝑀)2𝑁−1
variance
If a 95% confidence interval for the mean difference score in a paired samples t-test includes zero, then
we cannot reject the null
If the test statistic we obtain is unlikely (p < alpha) given the null hypothesis, then which of the following statements is TRUE?
we should reject the null hypothesis, the test statistic falls into critical region
Given no other information, is the sample mean an unbiased estimate of the population mean?
yes
Which of the following would be an example of a null hypothesis?
µ = 10
The researcher conducts a two-tailed test comparing her sample to a population with a mean of 40. Which of these can be the null hypothesis?
𝐻0H0: 𝜇=40
The null hypothesis for a paired sample t-test (two-sided) is
𝐻0H0: 𝜇𝐷=0
The alternative hypothesis for a paired sample t-test (two-sided) is
𝐻1H1 : 𝜇𝐷≠0
The researcher conducts a one-tailed t-test comparing his sample to a population with a mean of 50. Which of these could be the alternativehypothesis?
𝐻1H1: 𝜇>50, 𝐻1H1: 𝜇<50
The test statistic for a goodness-of-fit test is...
𝜒2χ2 (chi-square)
When conducting a two-way ANOVA, how many null hypotheses are tested?
3
If the mean IQ is 100 with SD = 15, what is the approximate probability that a randomly chosen sample of 9 people will have a mean IQ more extreme than 110? Remember that extreme can refer to both extremely large and extremely small sample means.
4%
One-way, repeated measures ANOVA reports F(2,8)=3.23. How many participants were included in the study?
5
A 3 X 2 factorial design will have ______ different cell means.
6
A researcher tested the effect of self-esteem (high, medium, low) and a field of study (psychology, biology, chemistry, mathematics) on the first salary after college. What are the degrees of freedom for the interaction?
6
The quantitative GRE (Graduate Record Examination) has a mean of 150 and standard deviation of 9. What is the approximate percentile rank for a student who scored 155?
70th
Given the following regression equation, interpret the slope. 𝑌𝑖^=23.44−2.66𝑋𝑖
For every 1 unit increase in X, the model expects a 2.66 units decrease in Y.
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)
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 three or more levels
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.
Which scenario could be analyzed using a factorial ANOVA?
Kamal measures the impact of noise and task difficulty on a memory task.
When referring to the mean of a sample, researchers typically use the letter
M
Based on the data from current UO students, the University Admissions Office aims to predict how well new students are likely going to do in college (in terms of their overall college GPA) based on their SAT scores and high-school GPA. How will they analyze the data?
Multiple regression
Sasha wants to let her readers know how many observations she collected for a particular variable. The appropriate letter to represent this is:
N
The formula for calculating the degrees of freedom for an independent samples t-test is
N - 2
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?
New York, South Carolina, Kansas, Montana or Oregon
The figure below represents what type of relationships between A and B and the dependent variable? (crossing x-shape)
No main effects, but a significant interaction
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 null 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)
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)
Even if a treatment has no effect, it is still possible to obtain by chance an extreme sample mean that is very different from the population mean. What outcome is likely if this happens?
Reject the null and make Type I error
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?
Simple regression
If you obtain a sample mean of 21.54, how would you calculate the LOWER limit of the confidence interval?
Subtract 1.96*SE from the sample mean
Which variable should you plot on the x-axis?
The casual variable, if one exists.
The results of a t-test depends on the sample size. What happens as you increase sample size?
The critical value of t decreases, SE decreases
A researcher comparing the effect of DBT (Dialectical Behavior Therapy) on male and female depression clients yielded a t-value of t = -1.23. During analysis, the researcher labeled males as group 1 and females as group 2. Which of the following can be concluded?
The effect of DBT was greater for females, but the difference was not statistically significant
In a study comparing three types of chairs on subjective comfort ratings, the researchers obtained F(2,40) = 3.02. The critical value of F, Fcritical (2,40)= 3.23. What was the decision?
The null hypothesis was retained.
If a researcher reported a small range for the 95% confidence interval, you can conclude that
The researcher is fairly certain the obtained sample mean is close to the population mean
Based on the following output from an independent samples t-test, t(21) = 1.34, p >.05, CI = [-5.34, 14.30], what can you conclude?
There is not enough evidence that the samples were drawn from populations with different means., fail to reject null
Independent samples t-test reported t(20) = 1.45. We know that _____
There were 22 participants in the study, p value was greater than 0.05
Which of the following is true about the null and alternative hypothesis?
They make opposite predictions.
A statistically significant sex difference in spatial ability was found between males (n = 2500) and females (n = 2600) in South Africa. A Cohen's d value was obtained yielding a value of d = 0.13. What can we say about these results in the purview of this information?
This is a small effect, so the significant difference should be interpreted cautiously
Which of the following statements regarding hypothesis testing is TRUE?
We can only minimize error, not eliminate it.
The degrees of freedom for a 𝜒2χ2test of independence is equal to...
(number of rows - 1) x (number of columns - 1)
Jeremiah is conducting a 2 × 3 ANOVA on the relationship between athletic status (athlete, nonathlete) and socioeconomic status (low SES, mid SES, and high SES) on physical symptoms. What are the degrees of freedom for the effect of socioeconomic status?
2
A 3 X 2 factorial design indicates that there are...
2 IVs; one with 3 levels and one with 2 levels
A one-way ANOVA is used to test for mean differences between/among ________________________________.
2 or more groups
Given a normal distribution, what is the area under the curve between -1 and +2 standard deviations from the mean?
82%
In which of these scenarios would a researcher use a one-sample t-test?
A personality psychologist compares whether levels of consciousness in a random sample of college students at her college differ from the known mean of a typical student.
In which of these scenarios would a researcher use an independent samples t-test?
A personality psychologist tests for sex differences in consciousness scores in young adulthood.
For which of the following would a paired samples t-test be appropriate?
A researcher measures working memory capacity for each participant before and after a sleep intervention.
Which combination of factors will produce the most extreme t-statistic?
A small sample and a large standard deviation
Which of these observed values are more likely to lead to rejecting of the null hypothesis?
A very small p-value, large F-value
Under what circumstances will be the absolute value of the t-statistic the largest?
Big differences between means, large sample size
The most commonly used measure of effect size for independent samples t-test is
Cohen's D
Which of the following is a general definition of Cohen's d?
Cohen's D
The most commonly used measure of effect size for an independent samples t-test is
Cohen's d
_________________ statistics describe the data from our sample. ________________ statistics use sample data to estimate characteristics of the population
Descriptive; Inferential
Which of the following questions would be most likely be tested using a paired samples t-test?
Effect of cognitive-behavioral therapy on depression
When p-value is _________, we will retain the _________ hypothesis.
above 0.05, null
The difference between the formula for the one-sample t-test statistic and the z-test statistic is that the one-sample t-statistic uses
an estimated standard error
In a one-way ANOVA, MS within can be viewed as....
an estimator of the error variance σ^2
Which of the following tests are commonly used for finding an association between one nominal variable and one continuous variable? Select all that apply
anova, t-test
Marlieke measured extraversion on a six-point scale in a sample of Dutch college students. She found the mean to be 3.53. Can we conclude at alpha = 0.05 that Dutch students are less extraverted than Americans? American population parameters for extraversion are µ = 3.84, 𝜎σ = 1.18.
answer depends on sample size
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
In a factorial ANOVA analysis, variability due to row, column, and interaction effects is considered ______-groups variability.
between
The results from a factorial ANOVA will allow researchers to examine:
both main and interaction effects.
The shape of F distribution under the null hypothesis is determined by...
both within and between groups degrees of freedom
You are interested in learning if people drink because they think it will increase their sociability levels. To investigate this, you survey 150 people and get the following results: 75 people drink and think they are sociable, 20 people drink and don't think they are sociable, 30 people do not drink and think they are sociable, and 25 people do not drink and do not think they are sociable. Which statistical test you would use to answer the research question and/or analyze the data described?
chi-square test of independence
Some additional, unmeasured variable that relates to the independent variable and may also cause changes in the dependent variable is called a _______________.
confound
A psychologist is interested in the relationship between job satisfaction and stress. Within a large corporation, the psychologist asked a random sample of workers two questions. The first question asked workers to rate their overall satisfaction with their job on a scale from 1 to 50. The second question asked the workers to rate their stress level during the past week on a scale from 1 to 50. What type of statistical test best assesses the strength of the relationship between job satisfaction and level of stress?
correlation
A researcher wants to test the relationship between income, measured in dollars earned per year, and social connectedness, measured in the number of friends a person has. Which statistical test you would use to answer the research question and/or analyze the data described?
correlation
Choose the right test for testing the relationship between two variables: two continuous
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. Which inference test will be used to analyze the data?
correlation
As sample size increases, standard error _____________, because your sample estimates are closer to the actual population value.
decreases
In a one-way, repeated-measures ANOVA, the degrees of freedom associated with the remaining variability (after variance due to individual differences and the independent variable are factored out )are called _____.
dfResidual
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
The null hypothesis for an independent samples t-test states that the difference between the population means is
exactly zero
We can only run a chi-square test if the ____________ is at least 5.
expected frequency in each cell
Two-way ANOVA is also known as.....
factorial ANOVA
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
The t-distribution, especially at lower levels of degrees of freedom, has ____________________ than the normal distribution.
fatter tails
Researchers wanted to compare the level of happiness in US and Finland. Which of the following statistical tests would be appropriate for this analysis?
independent samples t
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
An ecologist obtained a random sample of 85 small rural towns and a random sample of 72 small suburban towns. For each town, he calculated pounds of trash per resident per year that went to the landfill. What statistical test will he use to see if rural and suburban residents differ in how much trash they generate every year?
independent samples t-test
For which of the following tests does the calculation of the t-statistic require a pooled standard deviation measure?
independent samples z
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
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
To be honest, Likert scales, such as "rate how outgoing you are on the scale from 1 to 5", are ordinal. But we treat them as _______________ .
interval
Which measure of central tendency always changes if one score changes?
just mean
Which situation will lead to the largest F-statistic?
large differences among group means and small within-group variability
With a very small sample size, you would have a _____________ standard error, which would yield a ______________ confidence interval for the estimate.
large; wide
A(n) _____ effect is the effect of a single explanatory variable on a dependent variable.
main
What value always has a z-score of 0?
mean
According to the Cohen's rule-of-thumb interpretation of r-values, an r of -.3 is considered a ___________________ correlation.
moderate
In a one-way, repeated-measures ANOVA, which equation is used to calculate dfSubjects?
n-1
In the equations for population variance and standard deviation, "N" in the denominator refers to the number of observations for a given variable. However, when calculating variance or standard deviation for a particular sample, we use _____________ to account for bias.
n-1
A correlation coefficient r = 0 indicates
no relationship
Imagine you are a psychologist at a track-and-field event. Match the scale of measurement with the appropriate variable.
nominal: color, ordinal: places, interval: judges scores, ratio: time
When looking at a line graph of a 2 × 2 ANOVA, what would indicate that a possible interaction exists?
non parallel lines
In a 𝜒2χ2test of independence, the __________ hypothesis states that the probabilities of one variable do not depend on the value of another variable.
null
Correlation and linear regression are used to analyze the relationship between ________________ predictors and __________________ outcomes.
numerical; numerical
In a one-way ANOVA, the outcome variable must be.....
on interval or ratio scale
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
The assumptions for paired t-test are very similar to the assumptions for a
one sample t test
Academic Support Services was interested in doing a study to determine if the location where a student studies for exams affects his or her test performance. All subjects were randomly assigned to one of three conditions: study in your dorm room, study in the student union, or study in the actual classroom where the test will be administered. The students' test scores were compared. Which statistical test you would use to answer the research question and/or analyze the data described?
one-way between subjects ANOVA
A researcher is interested in the age at which infants learn to recognize faces. He decides to measure infant age as "number of days since birth". This represents the researcher's ____________________ definition
operational
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 the variance.
original
The probability of obtaining a test statistic at least as extreme as the one we did given the null hypothesis is known as...
p value
Which of the following is used to decide whether to reject or retain the null hypothesis?
p value, critical value
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 sample t test
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
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 samples t-test
A demographer hypothesized that men and women in a heterosexual relationship differentially support same-sex marriages. He randomly sampled 250 heterosexual couples and asked each wife and each husband to indicate their support for same-sex marriages on a 10-point scale. Which test should the demographer use?
paired t-test
What value is obtained if you sum all of the squared deviation scores from a population and then divide that sum by N?
population variance
What term is used to describe the shape of a distribution in which the scores pile up on the left-hand side of the graph and taper off to the right?
positively skewed
The probability of rejecting a null hypothesis that is false is called...
power
The standard error is _____
proportional to the standard deviation of the population, linked to sample size, the standard deviation of the sampling distribution of means
By following two groups of people, one group who smokes (and smoked before entering the research study), and one group who doesn't smoke (and never smoked before entering the research study) a researcher is engaging in _________________ research. Check all that apply.
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
A researcher conducted a single-sample t-test and found t(23) = 2.24. The critical t-value for a two-tailed, one-sample t-test with an alpha level of .05 and 23 degrees of freedom is 2.07. What is the conclusion?
reject null
A researcher reports the following results from a paired samples t-test (two-tailed, alpha = .05): t(31) = 3.44, p = .021 What should the researcher conclude?
reject null
Given the results r(29) = .44, p < .05, what do we know?
reject null, If we ran the regression analysis, the b (slope) coefficient would be positive
f 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