Cognitive biases: How much are we influenced by previous rating? Effect of previous rating on the following "quality" of the movie.

This thesis examines whether our choice of movie rating is influenced by previous rating based on a simple web experiment. There are 2 groups - group of laymen from the ranks of students and group of active movie fans. Each participant was randomly distributed into one of 3 subgroups in his group. There is a control subgroup with no previous rating, a treatment subgroup with low previous rating and a treatment subgroup with high previous rating. In 3 out of 4 treatment subgroups there was found out using regression analysis significant change of average rating in comparison to control subgroups by more than 1 point on scale 1 to 10. There wasn´t found out smaller bias towards previous rating in group of movie fans, which was the reason why this group had been added. Subgroups with low previous rating influence average rating in both groups, subgroups with high previous rating only in group of active movie fans