What are the weaknesses and strengths of cross-sectional and longitudinal reseach designs?

LONGITUDINAL

Strengths

• Gathers rich, detailed data
• Shows trends over time
• Removes participant variables (because the participants stay the same)
• High ecological validity (set in the real world)
• Explores developmental changes

Weaknesses

• Time consuming, therefore expensive
• Sample attrition - often the most interesting participants drop out
• Experimenter bias - tendency to get close to the participants
• Ethical issues - can put pressure on participants or influence their life choices

CROSS-SECTIONAL STUDIES

Strengths

• Quick, easy, therefore cheap
• No sample attrition
• Avoids ethical pressure or experimenter intimacy

Weaknesses

• Cohort effects - some groups at a particular stage are untypical
• Unreliability - snapshot on a particular day may be unrepresentative
• Superficial - no depth to the data