Question

scientists conduct a study in which 100 adults with chronic diarrhea are divided into 2 groups with 50 people per group. one group is given a supply of yogurt that contains a certain kind of bacteria, and the other group is given yogurt that is bacteria - free. the studys participants and researchers do not know which group of subjects has the bacteria in the yogurt and which group does not. the scientists instruct the participants to eat the entire 8 ounces of yogurt once a day for a month and record their bowel habits. this is an example of a(n) ______ study. multiple choice uncontrolled introspective hypothetical double - blind

Explanation:

A double - blind study is one where neither the participants nor the researchers know which group is receiving the treatment (in this case, the yogurt with bacteria) and which is receiving the placebo (bacteria - free yogurt). In this study, both the participants and the researchers are unaware of the group assignments, which fits the definition of a double - blind study. An uncontrolled study lacks a control group, which is not the case here. An introspective study involves self - examination of one's own thoughts and feelings, which is not relevant. A hypothetical study is based on hypotheses rather than actual experimentation with participants, which also does not fit.

Answer:

D. double - blind