PSY 1101 Lecture Notes - Lecture 1: Sample Size Determination, Lobectomy, Blind Experiment

• School: University of Ottawa
• Department: Psychology
• Course: PSY 1101
• Professor: Kenneth Campbell

Document Summary

Lecture 5: scientific methods (cont"d; sep. 24 2015) If this ratio is large enough, the difference is said to be statistically significant. The researcher must indicate what is the probability of finding a difference this large by chance alone. Example: the level of significance is set at 0. 05. A statistician might claim that differences this large could only occur by chance on 5% of occasions. If we could run the experiment 100 times, we would find differences (between the means) this large just by chance (simply by the subjects we randomly select) only 5 times. Null hypothesis: violent video will have no effect on children"s aggressions. Psychoanalytic/freud hypothesis: violent video will cause a decrease in children"s aggression. Social modelling hypothesis: violent video will cause an increase in children"s aggression. Ensure explained variance is large (the size of the experiment effect) Larger differences are more likely to be significant. We are much more confident with results from large than small samples.