8/20 HW: Quasi-experiments and Correlational Studies

Bidirectional Ambiguity

Uncertainty in correlational research about the direction of the relationship between variables—whether variable A causes B, B causes A, or a third variable influences both

Confounding Variable

A variable other than the independent variable that might influence the dependent variable, reducing internal validity

Correlation

A statistical relationship or association between two variables, indicating how they change together. It can be positive, negative, or zero (no correlation)

Correlational Study

A non-experimental research design used to observe and measure relationships between naturally occurring variables without manipulating them

Curvilinear Relationship

A relationship where the variables increase together up to a certain point, then as one continues to increase, the other decreases. Often represented by an inverted U shape

Cross-Sectional Design

A type of quasi-experimental study that examines different groups (e.g., age groups) at a single point in time to identify developmental or group-based differences

Ecological Validity

The extent to which research findings can be generalized to real-life settings

Generalizability

The degree to which findings from a study can be applied to broader populations or different contexts

Internal Validity

The extent to which a study can demonstrate a cause-and-effect relationship by controlling for confounding variables

Longitudinal Cohort Design

A study design that involves repeated observations of the same individuals over an extended period to track developmental or behavioral changes

Natural Experiment

A type of quasi-experiment where the independent variable is an environmental or naturally occurring event that is outside the researcher’s control (e.g., policy changes, natural disasters)

Non-Equivalent Control Group Design

A quasi-experimental design where participants are assigned to groups based on traits or behaviors, rather than random allocation, such as comparing individuals with and without a diagnosis

Pearson’s r

A statistical measure that indicates the strength and direction of a linear correlation between two variables. Ranges from -1 (perfect negative) to +1 (perfect positive)

0 means no correlation

Positive Correlation

A relationship where both variables increase or decrease together

Negative Correlation

A relationship where one variable increases while the other decreases

Pre-test/Post-test Design

A research method where measurements are taken before and after an intervention or naturally occurring event to observe changes over time

Psychometric Tests

Standardized tests used to measure mental capabilities or characteristics such as intelligence, mood, or personality traits

Quasi-Experiment

A study that examines the effect of an independent variable without random assignment. Participants are grouped based on characteristics like age, gender, or treatment preference

Regression Analysis

A statistical method used to determine the line-of-best fit on a scatterplot and examine the strength of relationships between variables

Scatterplot

A graph used to display the relationship between two quantitative variables, where each point represents an observation