The 7Eleven stores in New York City let their customers answ

The 7-Eleven stores in New York City let their customers answer a weekly question by choosing to have their coffee in a cup labled \"yes\" or \"no\". A January 1990 survey asked if Congress deserved a pay raise, illustrating the question with a picture of a fat congressman lighting up a cigar with a $100 bill. 71% of the 682,295 persons served chose a \"no\" cup.

Any potential sources of bias? If more than one source of bias is present, select the more serious source of bias.

Response bias is possible. The study was conducted in such a way as to achieve a desired response that may be different from the population in general.

Under coverage bias is possible. Since only people that dring coffee were polled, their answer my differ from the general population.

There is no indication of bias.

Unresponse bias is possible. Since people that do not drink coffee were not surveyed, the study may misrepresent the general population.

Solution

d.)Unresponse bias is possible. Since people that do not drink coffee were not surveyed, the study may misrepresent the general population.