Question

7. Do diet sodas contribute to obesity? Researchers recruited 1,200 randomly selected college students at state universities in Texas to participate in a four- year study looking at the relationship between diet soda and obesity. At the start of the study, students were weighed and interviewed. After interviews w the students, participants were classified as either regular soda drinkers, diet soda drinkers, or non-soda drinkers. Four years after the interview, the students were contacted again and reweighed. The weight gains were then compared between the diet soda drinkers and non-soda drinkers. This study appears to be: an experiment based on a matched pairs design an experiment based on a completely randomized design an experiment based on a randomized block design an observation study based on a simple random sample e an observational study based on a stratified random sample

Answer 1

In an observational study investigators observe subjects and measure variables of interest without assigning treatments to the subjects. The treatment that each subject receives is determined beyond the control of the investigator.

This is an observational study as there

Simple random samples involve the random selection of data from the entire population so each possible sample is equally likely to occur. In contrast, stratified random sampling divides the population into smaller groups, or strata, based on shared characteristics.

This is simple random sampling

hence

option D) is correct