Experimental Design - ACT Science

Double-blind procedure. Prevents conscious or unconscious researcher bias.

To reduce order effects and time-related confounding. Random order prevents time-dependent confounding.

A condition expected to produce no response. Confirms no false positive responses occur.

A factor kept constant across all experimental conditions. These prevent confounding effects from other variables.

Prevents expectations from influencing results. Eliminates unconscious influence on data collection.

The extent to which results generalize to other contexts. High external validity means results apply beyond the specific study conditions.

Crop yield. Crop yield is the outcome measured to assess fertilizer effectiveness.

Independent variable. The researcher controls this to test its effects.

A variable that is manipulated to observe its effect. This is the cause or input that researchers control.

A variable that is measured and affected in the experiment. This is the outcome or response being studied.

Assigning subjects to groups by chance to reduce bias. Ensures each participant has equal chance of any group.

Neither participants nor researchers know group assignments. Prevents bias from expectations of both groups.

A harmless substance given to control group to mimic treatment. Controls for psychological effects of receiving treatment.

Repeating an experiment to verify results. Confirms findings are consistent and reliable.

An extraneous variable that affects the outcome, obscuring results. Makes it impossible to determine true cause of results.

Increases reliability and reduces sampling error. Larger samples better represent the target population.

To ensure that each member of the population has an equal chance of selection. Prevents selection bias in choosing participants.

Numerical and can be measured. Allows statistical analysis and precise comparisons.

Line graph. Shows trends and patterns in continuous data.

Independent variable. This is what the researcher changes or controls.

Dependent variable. This shows the effect of the manipulation.

Variables are regulated to prevent confounding effects. Eliminates alternative explanations for results.

Defines how variables are measured and observed. Ensures consistent measurement across all studies.

Dependent variable. This measures what happens due to treatment.

Experimental group. This group gets the treatment being tested.

Randomization. Random assignment eliminates systematic differences.

Double-blind procedure. Neither group knows treatment status to prevent bias.

Participants do not know their group assignment. Only participants are unaware of their group.

To increase the generalizability of results. Results apply more broadly with diverse samples.