1. More dogs are being diagnosed with thyroid problems than have been diagnosed in the past. A researcher identified 50 puppies without thyroid problems and kept records of their diets for several years to see if any developed thyroid problems. This is ain't

O randomized experiment

O observational prospective study

O survey

O observational retrospective study

2.
The owner of a car dealership planned to develop strategies to increase sales He hoped to loam the reasons why many people who visit hrs car lot do not eventually buy a car from him. For one month ho asked his sales staff to keep a list of the names and addresses of everyone who came in to test drive a Car. At the end of the month ho sent surveys to the people who did not buy the car. asking them why. About one third of them returned the survey, with 44% of those indicating that they found a lower once elsewhere. Which is true?

I. The population of interest is all potential car buyers

II. This survey design suffered from non response bias Check the best answer.

a. Only I

b. neither

c. I and II

d. Only II