Practice- Independent and Dependent Variables
Remember: Time is frequently used as the independent variable. The dependent variable will
change over time (this “change” is what the researcher measures/records).
Sample Problem: A scientist want to study the diversity of soil bacteria found during different
months of the year.
a. What is her Independent variable? _______________________________________
b. What will be her Dependent variable? ____________________________________
Questions. Identify the dependent and independent variables in the following examples.
1. Height of bean plants is recorded daily for 2 weeks.
a. Independent variable: ________________________________________________
b. Dependent variable: _________________________________________________
2. Guinea pigs are kept at different temperatures for 6 weeks. Percent weight gain is
recorded.
a. Independent variable: ________________________________________________
b. Dependent variable: _________________________________________________
3. The diversity of algal species is calculated for a coastal area before and after an oil spill.
a. Independent variable: ________________________________________________
b. Dependent variable: _________________________________________________
4. Light absorption by a pigment is measured for red, blue, green, and yellow light.
a. Independent variable: ________________________________________________
b. Dependent variable: _________________________________________________
5. Batches of seeds are soaked in salt solutions for different concentrations and germination
is counted for each batch.
a. Independent variable: ________________________________________________
b. Dependent variable: _________________________________________________
6. An investigator hypothesizes that the adult weight of a dog is higher when it has fewer
littermates.
a. Independent variable: ________________________________________________
b. Dependent variable: _________________________________________________