1. The results of a one-sample hypothesis test are reported as follows: t(18) = 2.25, p < .05. Based on this report, what was the statistical decision and how big was the sample?
A. The null hypothesis was rejected using a sample of n = 18.
B. The null hypothesis was rejected using a sample of n = 19.
C. The null hypothesis was not rejected using a sample of n = 18.
D. The null hypothesis was not rejected using a sample of n = 19.
2. A hypothesis test produces a t statistic of t = 2.14. If the researcher is using a two-tailed test with a = .05, how lard does the sample have to be in order to reject the null hypothesis?
A. At least n = 13
B. At least n = 14
C. At least n = 15
D. At least n = 16
3. What value(s) for t would be used for a point estimate of a population mean using a single-sample t statistic?
A. t = 0
B. t = +/-1.00
C. t = +/-1.96
D. Cannot answer without additional information
4. As sample variance increases, what happens to the likelihood of rejecting null hypothesis and what happens to measures of effect size such as r^2 and Cohen's d?
A. The likelihood increases and measures of effect size increase.
B. The likelihood increases and measures of effect size decrease.
C. The likelihood decreases and measures of effect size increase.
D. The likelihood decreases and measures of effect size decrease.
5. A researcher computes the pooled variance for two samples and obtains a value of 120. If one of the samples has n = 5 scores and the second has n = 10 scores, then what is the value of the estimated standard error for the sample mean difference?
A. The square root of (120/15)
B. The square root of (120/13)
C. The square root of (120/5 + 120/10)
D. The square root of 120/4 + 120/9)
6. What is the estimated standard error for the independent-measures t statistic for the following two samples? Sample 1: n = 4 with SS = 100. Sample 2: n = 8 with SS = 140.
7. Which of the following sets of data provides the clearest difference between the two samples?
A. One sample has M = 20 with s^2 = 10 and the other has M = 25 with s^2 = 10
B. One sample has M = 20 with s^2 = 5 and the other has M = 25 with s^2 = 5.
C. One sample has M = 20 with s^2 = 10 and the other has M = 30 with s^2 = 10.
D. One sample has M = 20 with s^2 = 5 and the other has M = 30 with s^2 = 5.
8. Assuming that there is a 5-point difference between the two sample means, which set of sample characteristics is most likely to produce a significant value for the independent-measures t statistic?
A. n1 = n2 = 25 and small sample variances
B. n1 = n2 = 25 and large sample variances
C. n1 = n2 = 100 and small sample variances
D. n1 = n2 = 100 and large sample variances
9. An independent-measures study uses two samples, each with n = 7, to compare two treatment conditions. The t statistic for this study will have degrees of freedom equal to ____.
10. For an independent-measures research study, interval estimation would be used to:
A. estimate the population mean
B. estimate the sample mean
C. estimate the difference between two population means
D. estimate the difference between two sample means
11. What is being estimated when using the independent-measures t statistic to construct a confidence interval?
A. The values for two unknown population means.
B. The values for two unknown sample means.
C. The difference between two population means.
D. The difference between two sample means.
12. Compared to an independent-measures design, a repeated-measured study is more likely to find a significant effect because it reduces the contribution of variance due to ____.
B. Degrees of freedom
C. the effect of the treatment
D. Individual differences
13. A repeated-measures experiment and a matched-subjects experiment both produce t statistics with df = 20. Which experiment used more subjects?
A. repeated measures
B. matched subjects
C. Both used n = 21 subjects
D. Both used n = 22 subjects
14. A researcher obtains 1 = 2.35 for a repeated-measures study using a sample of n = 8 participants. Based on this t value, what is the correct decision?
A. reject the null hypothesis with a = .05 but not with a = .01
B. reject the null hypothesis with either a = .05 or a = .01
C. fail to reject the null hypothesis with either a = .05 or a = .01.
D. cannot make a decision without additional information