16. The most scientifically valid research is ________ research. a. observation b. focus-group c. survey d. behavioral data e. experimental 17. All of the following are rules of thumb for questionnaire design EXCEPT ________. a. making questions as simple as possible b. making the questions specific c. ensuring that fixed responses overlap d. avoiding hypothetical questions e. avoiding questions with a negative in them 18. The most common instrument used to collect primary data is the ________. a. human eye (through observation) b. Internet c. bar-code reader (behavioral data research) d. video camera (e.g., focus-group research) e. questionnaire 19. Some marketers prefer more ________ methods for gauging consumer opinion because consumer actions do not always match their answers to survey questions. a. quantitative b. qualitative c. psychographic d. covert e. subliminal 20. A question that uses a scale that connects two bipolar words wherein the respondent selects the point that represents his or her opinion is called ________. a. a dichotomous question b. a multiple-choice question c. a Likert scale d. the semantic differential e. a word association question  Â