Dr. Lofgren was interested in the effects of test anxiety on…

Dr. Lofgren was interested in the effects of test anxiety on concentration abilities. Using an anxiety questionnaire, he measured student anxiety levels when the students arrived at his laboratory and then again immediately before taking an examination. Dr. Lofgren hypothesized that participants in his study would have higher anxiety scores immediately prior to the completion of the exam compared to when they first came in. As hypothesized, Dr. Lofgren found that participants’ anxiety scores were significantly higher immediately prior to the examination compared to baseline scores. As a result of this information, what type of t test was Dr. Lofgren MOST likely to use to test his hypothesis? Is Dr. Lofgren’s hypothesis test one-tailed or two-tailed? Explain your answers.

Marcus is testing to see if men and women send the same numb…

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?

Dietz and Henrich (2014) were interested in the impact of te…

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?