PSYC 3130 Lecture: Experimental Design and Interaction Effects

These flashcards cover key concepts related to experimental design, specifically focusing on independent variables, interaction effects, factorial designs, and interpretation of data in psychological research.

Independent Variable

A variable that is manipulated in an experiment to observe its effect on the dependent variable.

Interaction Effect

A situation in which the effect of one independent variable on the dependent variable changes depending on the level of another independent variable.

Crossover Interaction

A type of interaction where the effects of the independent variables cross over, indicating that the impact of one variable is dependent on the level of another.

Spreading Interaction

An interaction effect where the difference in the dependent variable across levels of one independent variable becomes larger as the levels of the other independent variable change.

Factorial Design

An experimental setup that involves two or more independent variables, allowing researchers to assess the interaction effects between them.

Main Effects

The direct effects of each independent variable on the dependent variable, ignoring other variables.

Overall Effects

The combined effect of all independent variables on the dependent variable, often akin to main effects.

Marginal Means

The average scores for each level of an independent variable, calculated across levels of other independent variables.

Main Effects in Factorial Design

Determined by comparing marginal means of each independent variable to assess their effects separately.

Interaction Effects Identification

Can be identified using tables and graphs by examining how the dependent variable changes across different levels of independent variables.

2x2 Factorial Design

A design that has two independent variables, each with two levels, resulting in four conditions (cells) to analyze.

Independent-Groups Factorial Design

A factorial design where different participants are assigned to each condition.

Within-Groups Factorial Design

A design where the same participants are used in all conditions.

Mixed Factorial Design

A design that combines elements of both independent-groups and within-groups designs.

Three-Way Factorial Design

An experimental design involving three independent variables, which allows for the examination of main effects and interactions among them.

Key Words in Factorial Design

Terms used in literature that indicate factorial design, such as 'interactions,' 'main effects,' or specific designs like '2x2'.

Estimating Marginal Means

A process used in analyzing factorial designs to evaluate main effects based on the average scores for levels of an independent variable.

Interpretation of Interaction

Describing how the effect of one independent variable depends on the level of another independent variable based on data or graphs.

Factorial Notation

A way to represent the number of independent variables and their levels in a study, such as '2 x 2' indicating two variables each with two levels.