longitudinal studies

• • Follows one group of people/ a person over a period of time,
  • Behaviour tested at beginning of study then regular intervals
  • Aim is to compare data of each test to see how time affects whatever is being tested
• strengths

  • Same group of participants used for whole study, so participants variable doesn't affect data
  • Best way of spotting developmental trends as tests are repeated at regular intervals/ findings compared
• weaknesses

  • Problem of attrition, participants may withdraw - disrupts study
  • Withdrawal of ppts can cause sample bias
  • Practical difficulties e.g. can be expensive, time consuming
  • If researchers change over time, then data collection and analysis may vary in strength