Longitudinal Studies

Longitudinal Research

Following the same group of individuals over an extended period of time and collecting data from them at various intervals to see changes over time.

Experiments with longitudinal design

An experimental group is given an intervention and some aspects of their psychology is compared over time to a control group not receiving intervention

Cross-sectional study

Compares people at different ages or stages by comparing different groups of participants at one point in time.

Cohort

A group of participants selected at the same age or stage

Cohort Effects

The group of participants being studied may not be the same as similar groups growing up in other time periods. This limits the temporal validity of our results, lowers our confidence when generalizing results from a sample in one time period.

Sample Attrition

The loss of participants from a sample over time. This may be due to many reasons such as losing contact, the desire to discontinue, being unavailable or death.

Strengths

• Allows development of the same individual over time to be studied

• Participants may feel more comfortable disclosing information as they know the researcher well

Weaknesses

• Studies can take years so aims of research may lose relevance due to societal changes

• Time-consuming, may need to offer incentives for participants