IB Psychology 1.2 Causality Key Definitions

A situation where two correlated variables could each be the cause of the other, and the design cannot tell which.

A relationship in which a change in one variable produces a change in another.

A relationship in which a change in the independent variable directly produces a change in the dependent variable.

An unmeasured variable that influences both the proposed cause and the proposed effect, producing a spurious correlation.

A statistical association between two variables, captured by the correlation coefficient r, which runs from -1 to +1.

A research design that compares groups on a pre-existing variable the researcher cannot manipulate or randomly assign.

Sorting participants into experimental conditions by chance, so each participant has an equal probability of being in any condition.

A research design that manipulates the independent variable, randomly assigns participants to conditions, and controls confounding variables.