Questions

type of test? Many people who try to quit smoking will switch to a lighter brand of cigarettes to try to reduce their intake of tar and nicotine. However, there is some evidence that switching to a lighter brand results in people smoking more cigarettes. A researcher examining this phenomenon recruits a sample of participants who smoke regular cigarettes. The number of cigarettes smoked each day is recorded first. Then each participant switches to a lighter brand. After switching, the researcher again records the number of cigarettes smoked per day. What do you do with the data to determine if people smoke more after switching to a lighter cigarette?

Dependent Samples t-test

T/F The degrees of freedom for the dependent samples t test is the total sample size minus one.

False

T/F: A 2 Way ANOVA is a statistical procedure used to test hypotheses concerning the variance of 2 group means for the levels of one factor

False

T/F: A one-sample z-test is used when the population standard deviation is unknown.

False

T/F: Linear regression is used to measure the extent to which a criterion variable causes changes in a predictor variable

False

T/F: Researchers directly control for the probability of committing a Type II error

False

type of test? Friedman and Rosenman (1983) classified personality as Type A or Type B. Type A is hard-driving, competitive, and ambitious. Type B is more relaxed and easy-going. One factor that differentiates these two personalities is the high level of frustration experienced by Type As. To demonstrate this phenomenon, separate samples of Type A and Type B people are recruited. Each individual completes a questionnaire measuring level of frustration in response to several hypothetical situations. What would you do to find out if the frustration scores of Type As are significantly different from the frustration scores of Type Bs?

Independent Samples t-test

A researcher is interested in studying commuting habits of students in college and wants to compare the mean commuting time for undergraduates with that of graduate students. They record the typical commuting time of 50 undergrads and 50 grad students. Which statistical test would you recommend?

Independent samples t-test

Using a two-way ANOVA with Factor A and Factor B, a researcher found that scores for Factor A varied across the levels of Factor B. In this study, the researcher found a significant

Interaction (A x B)

Using a two-way ANOVA, a researcher concludes that Factor A is significant, independent of Factor B. In this study, this researcher found a significant

Main effect of Factor A

A researcher asks a sample of brothers and sisters to rate how positive their family environment was during childhood. In this study, the differences in ratings between each brother and sister pair were compared. The type of design described here is called a

Matched Samples Design

Hypothesis testing assumes the ... hypothesis is true

Null

The term "between-persons" refers to

Observing different participants one time in each group

Type of test? Anderson and Ford (1986) randomly assigned 60 undergraduate participants to one of three experimental conditions: (1) playing a highly aggressive video game, (2) playing a mildly aggressive video game, and (3) no game. Afterward, all participants completed a questionnaire that included a measure of how hostile the participant felt at that moment. What would you do to find out if type of video game affected feelings of hostility?

One Way ANOVA

Type of test? A researcher is planning a psychological intervention study for a group of adolescents, but before she proceeds she wants to characterize her participants' depression levels. She tests each participant on a particular depression index with a known mean and standard deviation in the general population. She has recruited 40 participants to take part in the study. What should she do if she wants to know whether or not the group of interest (adolescents) has the same mean depression level as the general population?

One-sample z-test

Letter grades (A, B, C, D, F) have the following scale of measurement:

Ordinal

In hypothesis testing, a researcher can never:

Prove that his or her hypothesis is correct

Type of test? A longitudinal study was started in the late 1970s with adolescents. Many variables were measured at that time, including how popular each participant was in high school. Now that the participants are middle aged, researchers want to know if popularity in high school predicts how successful someone is in middle age. What would you do with the data to determine this?

Regression

Type of test? A researcher is interested in studying preparation for retirement. In particular, she wants to understand when people start to save for retirement. She asks people to self-report how old they were when they first started to save for retirement. She also collects other information from these people, including their physical health, happiness, optimism, quality of social network, current job satisfaction, and level of anxiety about retirement. All of these variables are measured on continuous scales. What would you do with her data to determine which factors are more important for predicting the age at which people start to save for retirement?

Regression

A researcher compares the difference in the amount of texting by students in class during the first week and last week of classes. The type of design described here is called a

Repeated Measures design

Two researchers (A and B) compute an independent samples t test. For both tests, the standard error is the same, but the mean difference between the groups is larger for Researcher A. Which test is more likely to result in a decision to reject the null hypothesis?

Researcher A

A teacher would like to know if class attendance is related to where students usually sit in the classroom. At the beginning of the semester, the teacher asks students to indicate where they usually sit in class (front, middle or back). At the end of the semester, students are asked to rate their class attendance on a scale from 1 to 10 with 1 being labeled poor and 10 labeled excellent. Identify the independent variable (IV) and indicate whether it is discrete or continuous.

Seating Location, discrete

If the group means are similar, then the variance of the group means will be ___.

Small

The absolute value of correlation coefficient tells you the ... and the sign tells you the ...

Strength, direction

A researcher computes a chi-square test for independence and estimates the following effect size: phi = 0.56. This effect size is

Strong

The standard deviation of a set of observations is 0, you can conclude...

That all observations are the same value

Homogeneity of variance is an assumption for the one-way between-subjects ANOVA. What does this assumption mean?

That the variance is equal in each population from which samples are selected

All other things being equal, as the degrees of freedom increase, what happens to the critical value for a dependent samples t test (or for any t test, for that matter)?

The Critical Value Decreases

Power is

The likelihood of rejecting a false null hypothesis

Which of the following statements regarding the null hypothesis is true?

The null hypothesis always makes statements about a population parameter

To compute a dependent samples t test, a researcher has to know many values. Which of the following is NOT a value that the researcher must know to compute this test?

The population Standard deviation of difference scores

If the results of a statistical test indicate that we should not reject the null hypothesis, the most reasonable way to state the conclusion is

There is not sufficient reason to reject the null hypothesis

An instructor is interested in knowing if practice problems help students. Final exam score performance is compared for students who report doing all of the posted practice problems vs. students who report doing fewer than half of the problems.

This is not an experiment

T/F: Including two or more predictor variables into a single equation of a regression line can be more informative than an analysis using only one predictor variable

True

T/F: The regression line is always the best fitting straight line to a set of data points.

True

T/F: The test statistic is the same for a chi-square goodness-of-fit test and a chi-square test for independence.

True

type of test? Gladue and Delaney (1990) studied drinking behavior of college students. Men and women in a popular college bar area were asked the number and types of drinks they had had and their weight, and the researchers used this information to compute estimated blood alcohol concentration (EBAC) for each person. Some participants were interviewed at 9 PM, some at 10:30 PM and some at midnight. What would you do to determine the effect of sex and time of night on EBAC?

Two Way ANOVA

A Type I error means

We Reject a true null hypothesis

A Type II error means

We failed to reject a false null hypothesis

In which of the following situations is the Central Limit Theorem not applicable?

When the sample is small, below 30, and the population is not normal

The method of least squares is used to determine the ... straight line to a set of data points

best-fitting

A researcher notes that the variability attributed to difference between group means is quite large. Which source of variation is the researcher referring to?

between-groups

As sample size increases, the standard error of the mean..

decreases

The purpose of inferential statistics is to

draw conclusions about a group that is too large to measure

degrees of freedom for the sample standard deviation

equal to the sample size minus 1

Which of the following is true for a negatively skewed distribution?

median > mean

T/F: Two types of estimation are point estimation and interval estimation

true

A professor gives an exam in which the mean score is 78. She gives another exam to test whether or not the scores change. The null hypothesis is represented by

u = 78

You find a correlation of .32 between the number of hours since people's last meals and the number of potato chips the eat. This means that ... of the variance in potato chips eaten is ... by hours since last meal

...10%, explained

What is the standard deviation of 3.5, 4.0, 2.1, 3.2? Round answer to 2 decimal places

.8

If we draw two samples from the same population, one with 100 cases and one with 25 cases, for which sample will the estimate of the standard error of the mean tend to be smaller?

100 cases

There are... cells/groups in a 3 X 4 ANOVA design

12

A researcher reports the following regression line Y=12.03 + .48x, What value is the intercept

12.03

If the Person r between x and y is .4, what percentage of the variability in Y is explained by X

16% .4^2

A 2 X 3 chi-square test for independence has ___ degrees of freedom?

2

There are... factors in a 2 X 3 ANOVA design.

2

Correct Numerator and denominator degrees of freedom for an ANOVA with 10 participants in each of 4 groups

3 and 36 degrees of freedom k-1 , N-K N=40 K=4

A researcher conducts a study in which k = 5 and N = 80. What are the degrees of freedom between-groups for the one-way ANOVA?

4

The sample distribution of the sample mean is

A distribution of all sample means that could be obtained in samples of a given size from the population

A researcher plans to conduct a research study comparing 2 treatment conditions with a total of 20 scores in each treatment. Which of the following designs would require the smallest number of participants? a. independent groups design b. a repeated samples design c. a matched subjects design d. b and c e. a b and c

A repeated samples design

What is one of the distinctions between a population parameter and a sample statistic?

A sample statistic changes across samples, but a population parameter remains fixed

The probability of committing a Type I error is stated by ; the probability for committing a Type II error is stated by

Alpha; Beta

If we specify a range of values within which a parameter (such as a population mean) is likely to fall, this range can be referred to as

An interval estimate

If we draw 1,000 samples of size 100 from a population and compute the mean of each sample, the distribution of sample means will tend to be

Approximately normal in shape

A student's final grade in FREN 102 is 80. That student's final grade in CHEM 102 is 72. Is the student better at French or Chemistry? (FREN 102 final grade distribution: M = 82.5, s = 4.3; CHEM 102 final grade distribution: M = 61.9, s = 6.4). Assume grades were normally distributed.

Chemistry

Type of test? A recent survey found that 35.6% of US voters said they were Republicans and 33.5% said they were Democrats. Imagine that we ask college students to say if they consider themselves to be Republican or Democrat. What would we need to do to determine if political affiliation of college students differs from political affiliation of US voters in general?

Chi-Square Goodness of fit

Type of test? Selective liberal arts colleges produce many graduates who go on to obtain doctorate degrees, such as MD, JD, and PhD. Data are collected from students to find out how many completed a doctorate degree within 10 years of graduating. What would you do to determine if there is a relationship between sex (male or female) and completion of a doctorate degree (yes or no)?

Chi-square independence

type of test? We are interested in studying the relationship between attitude similarity and relationship satisfaction. A large number of couples are recruited for a study in which a scale is used to measure the amount of attitude similarity between partners (1 to 10 scale) and the amount of relationship satisfaction (0 to 30 scale). What would you do with the data to see if there is a relationship?

Correlation