Stats Final Exam

Estimated

A key difference between a t statistic and a z statistic is that the standard error is ______ to compute a t statistic.

only one design involves observing the same participants in each group

One difference between a repeated-measures design and a matched-samples design is that

the likelihood of rejecting a false null hypothesis

the power of the decision making process is

a one-way between subject ANOVA

A professor compared differences in class grades between students in their freshman, sophomore, junior, and senior years of college. If different participants were in each group, then what type of statistical design is appropriate for this study?

o reject the null hypothesis for an upper-tailed test, but to retain the null hypothesis for a two-tailed test

A professor finds that the average SAT score among all students attending his college is 1150 ± 150 ( ± ). He polls his class of 25 students and finds that the average SAT score is 1200. Suppose he computes a one-sample z test at a .05 level of significance. What is his decision?

Exam scores were significantly higher in the male group, t(18) = 2.12 p < .05

A professor teaches a certain section of material using a lot of examples with sports and cars to illustrate. He is concerned that this may have biased his instruction to favor male students. To test this, he measures exam grades from this section of material among women (n = 10) and men (n = 10). The mean score in the male group was 84 ± 4.0 (M ± SD); in the female group, it was 78 ± 8.0 (M ± SD) points. If the null hypothesis is that there is no difference in exam scores, then test the null hypothesis at a .05 level of significance for a two-tailed test.

Increase the power of the decision

Increasing sample size will

matched-samples design

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

retain the null hypothesis

A researcher computes the following one-way between-subjects ANOVA table for a study where k = 3 and n = 12. State the decision at a .05 level of significance.

2.53

A researcher conducts a study in which k = 6 and n = 6 per group. What are the critical values for the one-way between-subjects ANOVA at a .05 level of significance?

related-samples t test

A researcher conducts a study in which the population variance of difference scores between two groups is unknown. What type of t test is most appropriate for this study?

0.38

A researcher conducts a study using the one-way between-subjects ANOVA. He computes SSBG = 120 and SSE = 200. What is the effect size for this test using n^2?

27

A researcher measures attractiveness ratings of a male confederate among 30 women who were told the confederate was either single, dating, or married (n = 10 per group). What are the degrees of freedom for error for the one-way between-subjects ANOVA?

To retain the null hypothesis

A researcher obtains z = -6.45. What is the decision for a one-tailed test, upper-tail critical, at a .05 level of significance?

retain the null hypothesis

A researcher randomly assigned N = 16 rodents to experience one of four levels of shock (n = 4 per group) following the illumination of a visual cue. If SSBG = 24 and SSE = 48, then what was the decision at a .05 level of significance for a one-way between-subjects ANOVA?

two-independent-sample t test

A researcher records differences in ratings of emotion among participants watching either a drama or a romance film. Assuming that the population variance is unknown, what type of t test is appropriate for this study?

±2.110

A researcher records the level of attention among 18 students during an interactive and lecture portion of a single class. If she computes a related-samples t test at a .05 level of significance (two-tailed test), then what are the critical values for this test?

the p value or the test statistic

A researcher reports that scores were higher than the mean in the population, z = 1.60, p = .05 (d = 0.14). If this was a test at a .05 level of significance, then what value must be incorrectly reported?

d= 0.05; small effect size

A researcher reports that the mean time it takes to complete an experimental task is 1.4 ± 8.0 (M ± SD) s. If the null hypothesis was that the mean equals 1.0, then what is the effect size for this test using estimated Cohen's d?

Mean scores shifted 0.88 standard deviations from the population

A researcher reports that the size of an effect in some population is d = 0.88. Which of the following is an appropriate interpretation for d?

31

A researcher selects a sample of 32 participants who are assigned to participate in a study with one group. What are the degrees of freedom for this test?

analysis of variance

AOVA stands for

the critical value decreases

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

the population variance is unknown

As a requirement for the t test, researchers compute any type of t test with samples selected from populations in which

to reject the null hypothesis

Given the following values: = 10, M = 8, M = 0.5, conduct a one-sample z test at a .05 level of significance. What is the decision for a two-tailed test?

Significance testing

Hypothesis testing is also called

rejecting a true null hypothesis.

In Step 2 of hypothesis testing, researchers state a level of significance to minimize the probability of

prove that his or her hypothesis is correct.

In hypothesis testing, a researcher can never

all of these

In hypothesis testing, a researcher's decision

This advanced training seminar did not reduce response time, t(35) = -1.43, p > .05

The average response time to a bank robbery is about 9 min. A local community wants to improve on this time, so they implement advanced training seminars. They find that the new response time for a sample of 36 police officers is 8 ± 4.2 (M ± SD) min. Test whether this advanced training seminar reduced response time at a .05 level of significance.

level of significance

The criteria for a decision regarding the value stated in a null hypothesis is set by the

within-groups variability

The source of variability associated with error variance in the one-way between-subjects ANOVA is called ______.

The population variance must be known

To compute a one-sample 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?

n*k participants are each observed one time

Using a between-subjects ANOVA design, ______.

(nD - 1)

What are the degrees of freedom for the related-samples t test?

all of these

Which of the following is an assumption for computing a one-way between-subjects ANOVA?

all of these

Which of the following is an assumption for computing any type of independent-sample t test?

estimated standard error for difference scores

Which of the following is the denominator of the test statistic for the related-samples t test?

smaller

Without changing the value of error variance, the ______ the between-groups variability, the more likely we are to retain the null hypothesis.

Effect size

allows researchers to describe (1) how far mean scores have shifted in the population or (2) the percentage of variance that can be explained by a given variable.

one-sample t test

researcher records the number of distracters (such as noises) that preschool-aged children ignore while watching a popular Sunday morning cartoon show. Assuming that the population variance is unknown, what type of t test is appropriate for this study?