Psychological Research and Statistics Flashcards

Which scale of measurement has an absolute zero point that means the complete absence of the attribute?

Answer: Ratio

Ratio scales (e.g., height, reaction time) have a true zero, allowing meaningful ratio comparisons such as 'twice as long.'

A researcher uses a pretest-posttest control group design. Compared to a one-group pretest-posttest design, this controls for:

Answer: History and maturation threats to internal validity

Adding a control group that also experiences the passage of time and outside events controls for history and maturation, which affect both groups equally.

Construct validity of a psychological measure refers to:

Answer: The degree to which the measure actually assesses the theoretical construct it purports to measure

Construct validity is the extent to which a test measures the psychological construct (e.g., anxiety, intelligence) it was designed to capture.

When comparing three or more group means, why is ANOVA preferred over multiple t-tests?

Answer: Multiple t-tests inflate the familywise Type I error rate

Running multiple t-tests increases the probability of at least one false positive; ANOVA controls familywise error at the nominal alpha level.

In observational research, reactivity refers to the problem that:

Answer: Participants change their behavior when they know they are being observed

Reactivity (also called the Hawthorne effect) occurs when awareness of being observed alters participants' natural behavior.

A standardized score (z-score) of +2.0 means the raw score is:

Answer: Two standard deviations above the mean

A z-score expresses distance from the mean in standard deviation units; z = +2.0 indicates the score is two SDs above the mean.

External validity is MOST threatened in a study that uses:

Answer: A convenience sample of undergraduate psychology students

WEIRD (Western, Educated, Industrialized, Rich, Democratic) convenience samples limit the generalizability of findings to broader populations.