🧩 Chapter 4 – Research Strategies & Validity Save Groups

What do research strategies focus on?

Basic designs, external validity, and internal validity.

What is the purpose of descriptive research?

To provide a snapshot of what's happening without examining relationships among variables. Ex: A survey of student stress levels.

What does correlational (observational) research examine?

Relationships between two or more variables without manipulation or control.

What are the major problems in correlational research?

Third-variable problem, directionality problem, and spurious correlations.

What is a third-variable problem?

When an unseen factor causes both variables to change.

What is the directionality problem?

You can't tell which variable caused the other.

What is a spurious correlation?

A false relationship that appears due to multiple tests or chance.

What is an experimental design?

A design that manipulates an independent variable (IV) and measures a dependent variable (DV) with random assignment.

Why is random assignment important in experiments?

It controls individual differences and allows for causal inference.

What is a quasi-experimental design?

Similar to experimental, but lacks random assignment. Fixes directionality problem.

What issue remains in quasi-experimental design?

Third-variable problem.

What is external validity?

The extent to which study results can be generalized to other people, settings, or times.

What is self-selection bias?

Volunteers differ systematically (more curious, intelligent, higher SES, etc.).

What threatens generalizing to the real world?

Sensitization, self-monitoring, construct validity issues, and time of measurement.

What is internal validity?

The confidence that changes in the DV were caused by the IV.

What is assignment bias?

Preexisting differences between groups that distort results.

What are environmental confounds?

Uncontrolled differences in background environment (e.g., season, setting).

What are time-related variables?

Effects due to timing (e.g., morning vs. afternoon, learning/fatigue).

What is a Type I error?

False positive — concluding an effect exists when it doesn't.

What is a Type II error?

False negative — failing to detect a real effect.

What is statistical power?

The probability of correctly detecting a true effect (1 - β).

How are internal and external validity related?

They trade off — increasing one often decreases the other.

Which designs emphasize internal validity?

Experimental studies.

Which designs emphasize external validity?

Descriptive and correlational studies.