How do we measure change in psychology?
- In fields such as developmental psychology, change is an important factor, but how do we measure it?
- Behaviour may also change in response to certain stimuli, so it is an important concept to understand.
Prevalence
- Prevalence is the percentage of the population that exhibit certain traits.
- It gives us information about the scope and severity of different behaviours.
- We can also understand how different circumstances change behaviour.
- We can use prevalence to understand where and how to implement intervention/treatments.
Case study
According to the World Health Organization (WHO), 5.7% of adults suffer from depression.
Longitudinal & Repeated Measures Designs
- Longitudinal designs collect data about the same participants over a long period of time.
- Repeated measures designs aim to measure the same variable across participants in different conditions
Example
- If a longitudinal design were to be used to study different studying techniques on exam scores, researchers would collect data about the same group's studying techniques and exam scores throughout their years at school.
- If a repeated measures design were to do the same, they would instruct students to undergo exams after trying out different study techniques.
Critical Thinking
Note
Strengths of Longitudinal Designs
- Provides rich data and a comprehensive approach.
- Removes individual differences as a confounding variable.
Limitations of Longitudinal Designs
- Incredibly costly and time-consuming.
- Attrition (loss of participants over time) may affect generalizability of data.
Note
Strengths of Repeated Measures Designs
- Ability to use fewer participants.
- Removes individual differences as a confounding variable.
Limitations of Repeated Measures Designs
- If participants figure out the independent variable through repetition, demand characteristics may affect results.
- Practice, fatigue, and order effects may affect performance and results.
Reflection
Self review
- How do longitudinal and repeated measures designs differ?
