91影视

The survey has possible response bias because if people go often to the movies then they most likely don/t know the exact number of times that they went to movies in the past twelve months and thus they will have to estimate the amount.

A possible change would be to shorten the time from$12to3$ months or even to one month as people are then more likely to remember the exact number of times they went to the movies compared to using a long period such as a year.

The survey has possible selection bias because the people in the survey were only phoned while there are people in the survey were only phoned while there are people who do not have telephone and thus some people in the population will be excluded.

This would then most likely lead to an overestimation of the actual mean number of movies as people who do not own a phone are more likely to be poorer people and poorer people are less likely to be able to afford going to the movies.

The survey has possible non-response bias because some people who were phoned might not have picked up the phone or some people did not complete the survey.

This would then most likely lead to an underestimation of the actual mean number of movies as people who are not at home when they phone are more likely to have been at the movies and are more likely to go out frequently.