TYPES OF EXPERIMENTAL DESIGN



~INDEPENDENT MEASURES~

→ different participants are used in each condition of the independent variable (done by random allocation, so each participant has an equal chance of being assigned to a certain group)


+ Strengths

  • no issue with order effects and demand characteristics (compared to repeated measures)


- Limitations

  • subject to being affected by participant variables

  • less economical and more time-consuming, as you need 2X the number of participants (compared to repeated measures)




~REPEATED MEASURES~

→ the same participants take part in each condition of the independent variable


+ Strengths

  • fewer participants are needed (compared to independent measures), so it’s more economical


- Limitations

  • subject to demand characteristics as some participants may try to work out the aim of the study

  • subject to order effects




~MATCHED PAIRS~

→ each condition uses different participants but effort is made to match the participants in each condition in terms of key characteristics which may affect their performance


+ Strengths

  • low risk of demand characteristics and order effects


- Limitations

  • matching participants requires pre-testing which can be expensive and time-consuming