Conduct hypothesis testing:

1. A clinical psychologist thinks that depression affects sleeping patterns.To test this idea, she randomly selects 9 people with depression, and 8 people without depression (1 drops out of the study) and monitors their sleeping.The number of hours that each patient slept is presented below.Depressed:7.16.86.77.37.56.26.96.57.2Not-depressed:8.27.57.77.88.07.47.36.5Using alpha = .05, is there something to the psychologist’s intuition?Do people with depression sleep less than normal people?Conduct an hypothesis test that people with depression sleep less than non-depressed people.What is the size of the effect?
2. Albert Bandura, a famous psychologist, did a number of studies on aggression, children, and “observational learning.”In a series of studies, Bandura had some children watch a video in which an adult repeatedly hit, kicked, and threw a “bobo” doll (one of those weighted blow-up clowns).Other children watched a video of adults with the bobo doll, but the adults in the video did not hit, kick or throw the doll.The children were then placed in a playroom with the bobo doll and Bandura counted the number of times each of the children struck the doll.We recently did an identical experiment and the data are presented below:Video with Adults hitting bobo: 20, 65, 41, 80, 52, 35, 17, 34Video with Adults not hitting bobo: 5, 20, 0, 0, 10, 30, 0, 12

Bandura found that children who saw the video of the adults striking the bobo doll subsequently struck the doll more.Using alpha = .05, test the hypothesis that children who watch the video of adults striking the doll subsequently strike the doll more.Compute an estimate of effect size.

3.A recent study tested the effects of MDMA (“ecstasy”) on rats.Two groups of 15 rats were first trained to lever-press for sugar pellets.One group, the experimental group, then received an injection of MDMA prior to a test session, whereas the control group received a saline injection, prior to the test session.The number of lever presses made by each group during the test session are presented below:

Experimental: 178, 562, 451, 622, 98, 557, 363, 259, 214, 541, 577, 171, 208, 180, 601

Control: 335, 362, 401, 295, 420, 398, 345, 362, 344, 286, 387, 294, 312, 341, 350

Did MDMA have an effect on lever-pressing?Use an alpha = .05.