Psyc - 2317 : Study Guide Quiz 9 - Chapters 9 and 10

For the repeated-measures t statistic, df = _____.

N-1

​One sample has a variance of s2 = 10 and a second sample has a variance of s2 = 6. Which of the following most accurately describes the pooled variance for the two samples?

Somewhere between 6 and 10

For an independent-measures t statistic, the estimated standard error measures how much difference is reasonable to expect between the two sample means if the null hypothesis is true

True

For an independent-measures t statistic, you typically must compute the pooled variance before calculating the estimated standard error.

True

If both samples have the same number of scores (n), then the independent-measures t statistic will have df = 2n - 2

True

If the df value for an independent-measures t statistic is an odd number, then it is impossible for the two samples to be the same size

True

If the two samples are the same size, the independent measures t statistic will have an even number for degrees of freedom.

True

If the two samples are the same size, then the pooled variance will equal the average of the two sample variances.

True

One sample has n = 7 scores with SS = 40, and a second sample has n = 5 scores with SS = 80. The pooled variance for these two samples is 120/10 = 12.

True

​A research report states "t(15) = 2.31, p < .05." For this study, the sample had n = 16 scores.

True

​For a hypothesis test using a t statistic, the boundaries for the critical region will change if the sample size is changed.

True

​If two samples, each with n = 20 scores, are selected from the same population and both have the same mean (M = 53) and the same variance (s2 = 12), then they will also have the same t statistic.

True

​One sample has s2 = 12, and a second sample has s2 = 15. The pooled variance for these two samples will be between 12 and 15.

True

​The t distribution for df = 4 is flatter and more spread out than the t distribution for df = 20.

True

Which of the following research situations would be most likely to use an independent-measures design?​

​Compare the mathematics skills for 9th-grade boys versus 9th-grade girls.

​Under what circumstances can a very small treatment effect be statistically significant?

​If the sample size big and the sample variance is small

​When n is small (less than 30), how does the shape of the t distribution compare to the normal distribution?

​It is flatter and more spread out than the normal distribution.

​A researcher predicts that scores in treatment A will be higher than scores in treatment B. Which of the following is the correct null hypothesis for a one-tailed test evaluating this prediction?

​mA <= mB

Which of the following samples will have the smallest value for the estimated standard error?​

​n = 16 with s2 = 16

A researcher is using a two-tailed hypothesis test with α = .05 to evaluate the effect of a treatment. If the boundaries for the critical region are t = ± 2.080, then how many individuals are in the sample?​

​n = 22

A sample of n = 16 scores produces a t statistic of t = 2.00. If the sample is used to measure effect size with r2, what value will be obtained for r2?​

​r2 = 4/19

Which of the following is the correct way to report the results of a hypothesis test and a measure of effect size using a t statistic?​

​t(19) = 2.30, p < .05, r2 = 0.42

​A researcher reports an independent-measures t statistic with df = 30. If the two samples are the same size (n1 = n2), then how many individuals are in each sample?

16

​A researcher reports t(22) = 5.30, p < .01 for an independent-measures experiment. How many individuals participated in the entire experiment?

24

​What is the pooled variance for the following two samples? Sample 1: n = 8 and SS = 168; Sample 2: n = 6 and SS = 120

24

The following data were obtained from a repeated-measures research study. What is the value of MD for these data

3

A repeated-measures study comparing two treatments with a sample of n = 4 participants produces MD = 3 with SS = 48 for the set of difference scores. What is the repeated-measures t statistic for these data?

3/2 = 1.50

An independent-measures research study uses a total of 40 participants to compare two treatment conditions. What is the df value for the t statistic for this study

38

For a repeated-measures study comparing two treatment conditions, a researcher obtains a sample of n = 9 difference scores with a mean of MD = 4 and a variance of s2 = 36. What is the value for the repeated-measures t statistic for these data?

4/2

​Two samples, each with n = 16 scores, produce an estimated standard error of 4 points and a t statistic of t = 2.00. What is the sample mean difference?

8

A repeated-measures research study comparing two treatments with a set of 10 scores in each treatment will produce a t statistic with df = 18

False

An independent-measures study with n = 20 scores in each treatment will produce an independent-measures t statistic with df = 19.

False

If an independent-measures t statistic has df = 20, then there were a total of 18 individuals participating in the research study

False

The null hypothesis for the independent-measures t test states that there is no difference between the two sample means.

False

Two separate samples, each with n = 10 scores, will produce an independent-measures t statistic with df = 19.

False

f two samples each have s2= 10, then the pooled variance will be equal to 20

False

​If one sample has n = 5 scores with SS = 40 and a second sample has n = 5 scores with SS = 20, then the pooled variance will be 60/10 = 6.

False