1. do you think that a sample of 800 residents of a city with a population of 150, 000 is a large enough sample to analyze the voting habits of all residents? you know that those 800 people all answered a phone survey administered via a landline. i am concerned about selection bias, representativeness of the sample, and external validity of the study. do you think my concerns are valid? can you offer solutions that would allow me to work with the data set and not go out and survey additional residents?