Question

imagine that you would like to study the link between air pollution and number of emergency room visits for asthma symptoms. for this purpose, you choose one city with very high levels of air pollution and one city with very low levels of air pollution. in each city, you record the air quality index daily for two weeks and get several hospitals to provide the dates of emergency visits for asthma symptoms.

what is the independent variable?

what is the dependent variable?

what is the test group?

what is the control group?

Explanation:

Independent Variable:

The independent variable is the factor that is manipulated or varies independently to observe its effect on another variable. Here, air pollution (measured by air quality index) is the variable being compared between two cities (high vs. low levels) to see its impact on asthma - related emergency room visits. So the independent variable is air pollution (or air quality index).

The dependent variable is the one that is expected to change in response to the independent variable. In this study, the number of emergency room visits for asthma symptoms is what we expect to be affected by air pollution. So the dependent variable is the number of emergency room visits for asthma symptoms.

The test group is the group exposed to the factor being tested (the independent variable at the level we are interested in studying). Here, the city with very high levels of air pollution is the group where we are testing the effect of high air pollution on asthma - related emergency room visits. So the test group is the city with very high levels of air pollution.

Answer:

Air pollution (or air quality index)

Dependent Variable: