Bob wants to estimate the percentage of people who own a dog in his town, and he goes to all the apartment buildings to carry out his survey. He leaves out all the houses in the town. What kind of bias is this?

Nonresponse bias

Response bias

Bias due to undercoverage

Which of the following is the X variable in an experiment?

Group of answer choices

Independent variable, or factor

Confounding variable

Dependent variable, or response