Longitudinal and cross-sectional studies

What is a cross-sectional study?

Uses several groups of participants who are at different points in time. E.g. group of 5 year olds and a group of 10 year olds or a group of people starting psychotherapy and a group of people half-way through psychotherapy. The assumption is that the younger/earlier group WILL TURN INTO the older/later group in time.

What is sample attrition?

when the sample gets smaller because people are "dropping out" of the study as they wish to no longer participate for various reasons

What are the strengths and weaknesses of cross-sectional?

+ cheap quick and practical as no follow up study needed, studied once > avoid sample attrtition + participants easily obtained, pressure of longitudinal studies for participants to stay x individual differences x data collected from a snapshot in time so hard to identify developmental trends

What are the strengths and weaknesses of longitudinal studies?

+ same group of PPs means participant variables do not effect study + can spot developmental trends > can identify most beneficial types of therapy and treatment for patients x sample attrition x demand characteristics over long period x cohort may be only representative for its generation

What is a longitudinal study?

Longitudinal studies treat "time" as one of their independent variables (IV). It tests a group of people at different points in time.