1. Research has shown that losing even one night's sleep can have a significant effect on performance of complex tasks such as problems solving (Linde & Bergstroem, 1992). To demonstrate this phenomenon, a sample of n=25 college students was given a problem-solving task at noon on one day and again at noon on the following day. The students were not permitted any sleep between the two tests. For each student, the difference between the first and second score was recorded. For this sample, the students averaged an M_dif=4.7 points better on the first test with a standard deviation of SD_Dif=8 for the difference scores. Do the data indicate a significant change in problem-solving ability? Use a two-tailed test with =0.05.

Based on your results, what is the take-home message here and how does it relate to your life?

If results are significant at =0.05, would they also be significant if you used an alpha level of =0.01?