A medical researcher obtains a sample of adults suffering fr

A medical researcher obtains a sample of adults suffering from diabetes. She randomly assigns 63 people to a treatment group and 63 to a placebo group. The treatment group receives a medication over a period of three months and the placebo group receives a placebo over the same time frame. At the end of three months the patients\' symptoms are evaluated. The personnel director at a large company would like to determine whether the company cafeteria is widely used by employees. She calls each employee and asks them whether they usually bring their own lunch, eat at the company cafeteria, or go out for lunch. Based on previous clients, a marriage counselor concludes that the majority of marriages that begin with cohabitation before marriage will result in divorce. IQ test scores are normally distributed with a mean of 100 and a standard deviation of 13. An individual\'s IQ score is found to be 120. Find the z-score corresponding to this value.

Solution

As multiple questions are posted, only the 1st one will be answered.

30. As the researcher had decided whom to provide medication and whome to provide placebo, this is an example of an Experimental Study.

Answer: Experimental Study.

31. As the researcher took a survey and observed the responses, this is an Observational Study.

Answer: Observational Study.