Longitudinal Studies

Longitudinal Studies

1. What are they?

   • Longitudinal studies are a form of ongoing surveys
   • The researcher selects a sample and then collects data at regular intervals over a long period of time
   • They can show change over time, e.g. the 10 year census

2. Strengths

   • They avoid ethical problems, as participation requires informed consent and the agreement of those selected
   • By comparing earlier and later data from the same sample, you can see trends or change over time
   • It is more valid, as discrepancies can be checked against previous data

3. Weaknesses

   • It's difficult to obtain funding, because many funding agencies are reluctant to make long-term financial commitment
   • Samples are difficult to obtain because of the commitment required by the participants, and participants can withdraw at any time, reducing the sample size
   • As people know they are being studied, research may fall victim to the Hawthorne effect