Variables & Controls - ACT Science

Confounding variable. Uncontrolled variables can create false conclusions about cause and effect.

Dependent variable. Reaction time is measured as a response to the stimulus treatment.

Controls are used to minimize the effects of variables other than the independent variable. They isolate the effect of the independent variable by keeping other factors constant.

A control group is a group in an experiment that does not receive the experimental treatment. It serves as a baseline for comparison with the experimental group.

Independent variable. Fertilizer amount is manipulated to test its effect on plant growth.

Independent variable. Researchers deliberately change this variable to test its effects.

To test the effect of an independent variable on a dependent variable while controlling other variables. Controls ensure that observed effects are due to the independent variable alone.

Independent variable. Food type is the factor manipulated to observe its effect on energy.

Independent variable. Caffeine amount is manipulated to test its effect on alertness.

Dependent variable. Error count is measured as a response to sleep deprivation treatment.

To ensure that the results can be attributed to the experimental treatments rather than other factors. A proper control isolates the treatment effect from other influences.

It is kept the same throughout the experiment. Consistency eliminates it as a source of variation in results.

Independent variable. It's manipulated by the researcher and influences other variables.

Control variable. Constant temperature eliminates environmental variation as a factor.

Independent variable. Age is a factor that researchers can select or manipulate in their study design.

To reduce bias by evenly distributing confounding variables across groups. Random assignment prevents systematic differences between groups.

Dependent variable. The dependent variable responds to changes in the independent variable.

To prevent bias by ensuring neither participants nor researchers know who is receiving a treatment. It eliminates expectation effects that could bias results.

Dependent variable. This variable responds to changes in the independent variable.

To provide a standard for comparison against the experimental group. It establishes a baseline to determine if the treatment has an effect.

A constant is a factor that does not change throughout the experiment. Constants ensure that only the independent variable affects the results.

They help ensure that the results are due to the independent variable. Controls eliminate alternative explanations for observed changes.

A variable is any factor, trait, or condition that can exist in differing amounts or types. It can be qualitative or quantitative and varies between subjects or conditions.

It helps distribute confounding variables evenly across groups to minimize bias. Random assignment creates comparable groups and reduces selection bias.

It may distort the perceived effect of the independent variable on the dependent variable. It creates false correlations and misleading conclusions about causation.

To isolate the effect of the independent variable on the dependent variable. Control ensures observed changes are due to the intended treatment only.

Dependent variable. Speed is measured as a response to the brake type treatment.

To serve as a control treatment to compare against the effects of the drug being tested. Placebos control for psychological effects unrelated to the actual drug.

The changes made to the independent variable. The dependent variable responds to manipulations of the independent variable.