| Research Method | Description | Advantages | Disadvantages |
|---|---|---|---|
| Cros | People of different ages are studied at a single time | Not very tim | No need for continued retesting Possible confounding due to cohort effects (differences in performance between age groups caused by generational differences) |
| Longitudinal study | Same people are studied repeatedly over a long period of time | No possibility of cohort effects | Very tim Repeated testing has to be conducted Possible confounding due to changes in sample over time |