Which of the following is the correct null hypothesis for an independent-measures t test?
μ1 - μ2 = 0
A researcher reports t(22) = 5.30, p < .01 for an independent-measures experiment. How many individuals participated in the entire experiment?
One sample of n = 8 scores has a variance of s2 = 6 and a second sample of n = 8 scores has s2 = 10. If the pooled variance is computed for these two samples, then the value obtained ____.
will be exactly half way between 6 and 10
One sample has n = 10 scores and a variance of s2 = 20, and a second sample has n = 15 scores and a variance of s2 = 30. What can you conclude about the pooled variance for these two samples?
It will be closer to 30 than to 20
The data from an independent-measures research study produce a sample mean difference of 4 points and a pooled variance of 16. If there are n = 8 scores in each sample, then what is the estimated standard error for the sample mean difference?
The data from an independent-measures research study produce a sample mean difference of 6 points and an estimated standard error of 2 points. If there are n = 8 scores in each sample, then the value for the t statistic is ____.
An independent-measures research study uses two samples, each with n = 12 participants. If the data produce a t statistic of t = 2.08, then which of the following is the correct decision for a two-tailed hypothesis test?
Reject the null hypothesis with α = .05 but fail to reject with α = .01
For an independent-measures research study, what is measured by Cohen's d or r2?
The size of the difference between the two treatments
One sample has M = 18 and a second sample has M = 14. If the pooled variance for the two samples is 16, then what is the value of Cohen's d?
For an independent-measures t statistic, what is the effect of increasing the number of scores in the samples?
Increase the likelihood of rejecting H0 and have little or no effect on measures of effect size.
If other factors are held constant, which of the following sets of data would produce the largest value for an independent-measures t statistic?
The two samples both have n = 30 with sample variances of 20 and 25.
Which set of sample characteristics is most likely to produce a significant value for the independent-measures t statistic?
large mean difference and small sample variances
Two separate samples are being used to estimate the population mean difference between two treatment conditions. Which of the following would produce the widest confidence interval?
n1 = n2 = 10 with a pooled variance of 100
Which of the following confidence intervals also indicates a significant difference between treatments with α = .05?
Estimate that μ1 - μ2 is in an interval between 2 and 10 with 95% confidence
If both samples have the same number of scores (n), then the independent-measures t statistic will have df = 2n - 2.
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.
If an independent-measures t statistic has df = 20, then there were a total of 18 individuals participating in the research study.
If other factors are held constant, the larger the values for the two sample variances, the greater the likelihood that the independent-measures t test will find a significant difference.
An independent-measures study produces t(21) = 3.00, p < .01. For this study, if effect size is measured with r2, then r2 = 9/30.
Confidence intervals with the independent-measures t statistic are used to estimate how much difference there is between two population means