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If two sample means come from the exact same distribution, then the distribution of differences between means against which they will be compared should have a mean of:

Marcus is testing to see if men and women send the same number of text messages over the course of a day. He recruits 16 men and 31 women to be in his study. He finds that men send fewer text messages (M = 75, SD = 10) than women (M = 88, SD = 8). When Marcus conducts his t test, what is the pooled variance for this study?

Assume the following for a paired-samples t test: N = 16, Mdifference = 15.19, s = 23.2. What is the t statistic?

Dietz and Henrich (2014) were interested in the impact of texting on student learning. A group of 99 college students were randomly assigned to text (N = 50) or not text (N = 49) during a prerecorded psychology lecture. At the end of the 20-minute lecture, students answered a 17-question quiz about the material that had just been presented. Which statistical test should the researchers use to analyze their data?

As N increases, the width of the confidence interval increases.

Twenty-five college students experience the effects of alcohol on reaction time. They perform very basic timed responses in a driving simulator both before and after consuming several alcoholic beverages. The researcher collects a reaction time result for each of the 25 students before and after intoxication, for a total of 50 measures. What are the degrees of freedom for this study?

Why do we divide by N – 1 rather than by N when estimating a population standard deviation from the sample standard deviation?

The minimum acceptable level of estimated power for a study is:

The sample mean difference should fall at the center of the confidence interval for a paired-samples t test.

Which of the following statements about the Calvin cycle of photosynthesis is false?