Determine whether the study described is a randomized experiment or an observational study.

A math department chair wants to determine the effectiveness of online homework systems. She chooses four college algebra classes and assigns a different online homework system to three of the classes. class does not use any online homework system. She administers a common pretest and final exam to measure the effectiveness.

Choose the correct answer.

Randomized experiment

Observational study

Determine the type of bias involved.

A chancellor in a large metropolitan community college district interviews 100 employees to ask their opinion on her new initiatives and only two employees disapprove.

The type of bias involved in the given information is

(Choose one)

bias.

Determine the type of bias involved.

A radio host asks all the listening audience to call the city government to protest the potholes in the street outside the radio station. Over

3000

calls were made.

The type of bias involved in the given information is

(Choose one)

bias.

Randomized experiment or observational study? Do you think it is possible to design a randomized experiment to study this question, or will an observational study be necessary?

A scientist wants to determine whether people who live in places with high levels of air pollution get more colds than people in areas with little air pollution.

For this study:

An observational study will be necessary.

A randomized experiment is possible.