(UNFINISHED) Pg. 195-202; 204-206 Notes

Research that follows the same group of participants over a long period, measuring variables at multiple time points to detect changes.

A true experiment (with IV and DV) that is conducted over an extended period, measuring effects at multiple time points.
Combines experimental control with long-term tracking.

Longitudinal study – Often observational; no manipulation of variables; tracks natural changes over time.
Experiment with longitudinal design – Manipulates an independent variable and measures its effect over time, allowing for causal conclusion
- Cohort Effects: Differences in research results caused by participants being from different generations or life experiences, not by age or time passing.
Example: A 70-year-old today grew up with different technology than a 20-year-old, which may affect test performance.

Additional data collection after the main study to see if effects persist, change, or disappear over time.

Research that collects data from different groups at one point in time to compare them.
Example: Comparing memory ability in 20-, 40-, and 60-year-olds in a single session.

The loss of participants from a study over time.
Can reduce validity if those who drop out differ in important ways from those who remain.