Independent variable: manipulated factor. Dependent variable: measured response. Controlled variables: other conditions kept comparable. A comparison/control group helps determine what happens without the tested intervention.

A testable hypothesis makes a measurable prediction that observations could contradict. Random assignment helps balance preexisting group differences; random sampling concerns how participants are selected from a population. They solve different problems.

Replication tests reproducibility and reveals variability. Precision means repeated measurements cluster; accuracy means closeness to a true or accepted value. A tightly clustered but systematically wrong scale is precise but inaccurate.

Correlation alone does not establish causation. Consider confounding, selection bias, sample size, variability, measurement quality, and the uncertainty of estimates. A graph of two averages without sample sizes or variability is incomplete evidence. Separate the observation from the proposed explanation.

Practice: for every experiment, write “changed / measured / held similar / comparison / possible limitation.”

TEAS 7 practice test

10 minutes: recall yesterday’s concepts without notes.
20 minutes: read one or two lessons and work their examples.
20 minutes: answer a subject drill and explain each choice.
10 minutes: write why each miss happened: missing concept, misread detail, setup, calculation, or time.