Stats Exam 3

Which set of characteristics will produce the smallest value for the estimated standard error?

a large sample size and a small sample variance

Which combination of factors is most likely to produce a significant value for an independent-measures t-statistic?

large samples and small variance

If the null hypothesis is true, what value is expected on average for the repeated-measures t-statistic?

0

A sample of n = 4 scores has SS = 48. What is the estimated standard error for the sample mean?

2

An independent-measures study with n = 6 in each sample, produces a sample mean difference of 4 points and a pooled variance of 12. What is the obtained value of t?

2

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

24

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

24

The results of a one sample t-test are reported as follows: t(15) = 2.70, p < .05. Based on this report, how many individuals were in the sample?

16

A repeated-measures study and an independent-measures study both produced a t-statistic with df = 16. How many individuals participated in each study?

17 for repeated measures and 18 for independent measures.

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

If the sample mean difference is 3 points, which of the following sets of data would produce the largest value for Cohen's d?

Cohen's D is the same for all three of the samples

If other factors are held constant, which set of sample characteristics is most likely to reject a null hypothesis stating that μ= 80?

M=90 and small sample variance

For which of the following situations would a repeated-measures research design be appropriate?

comparing pain tolerance with and without acupuncture needles

If other factors are held constant, what is the effect of increasing the sample variance?

it will increase the estimated standard error and decreases the likelihood of rejecting H0

An independent-measures research study uses two samples, each with n = 12 participants. If the data produce a t statistic of tobt = 2.50, then which of the following is the correct decision for a two-tailed hypothesis test?

reject the null hypothesis with a=.05 but fail to reject with a=.01

Which of the following possibilities is a serious concern with a repeated-measures study?

the results will be influenced by order effects

One sample has n = 5 scores and the second has n = 10 scores. If the pooled variance for the two sample is 30, then what is the value of the estimated standard error for the sample mean difference?

the square root of (30/5+30/10)

What value is estimated with a confidence interval using the t-statistic (one sample t-test)?

the value for an unknown population mean

A researcher uses a repeated-measures design to compare individuals' performance before treatment with their performance after treatment. If all of the participants show improved performance of 8 or 9 points after treatment, then the researcher should find ____.

the variance of the difference scores is near zero

With α = .05 and df = 8, the critical values for a two-tailed t test are tcrit = ±2.306. Assuming all other factors are held constant, if the df value were increased to df = 20, what would happen to the critical values for t?

they would decrease. (move closer to 0)

A sample of n = 9 college students is used to evaluate the effectiveness of a new Study Skills Workshop. Each student's grade point average (GPA) is recorded for the semester before the workshop and for the semester after the workshop. The average GPA improved by MD = 0.60 points with s2 = 0.09. The researcher would like to use the sample to estimate how much effect the workshop would have for the entire college population. Which of the following is the 80% confidence interval for these data?

uD=0.60+0.10(1.397)