Mail surveys are particularly vulnerable to a problem that arises when not all respondents complete and return the survey. This problem is called

The ability that involves crystallized intelligence to the greatest extent is

solving an intellectual puzzle. interpreting a chemical formula. using words in an unusually creativity manner. analyzing relations between concepts.

A teacher is trying to see whether smiling at her students will increase the number of questions they ask. In the first and third week of the study, the number of questions students ask is recorded

In the second week, the teacher smiles a lot at her students, and the number of questions is also recorded. What type of research design is being used? a. within-subjects b. correlational c. placebo control d. between-subjects