experimental designs Flashcards
what is an independent groups design?
participants are allocated to different groups where each group represents one experimental condition
what is a repeated measures design?
all participants take part in all conditions of the experiment
what is a matched pairs design?
pairs of participants are first matched on some variables that may affect the DV. then one member of the pair is assigned to condition A and then other to condition B
what is random allocation?
an attempt to control participant variables in an independent groups design which ensures that each participant has the same change of being in one condition as any other
what is counterbalancing?
an attempt to control for the effects of order in a repeated measures design: half the particulars experience the conditions in one order, and the other half in the opposite order
strengths of an independent groups design
•order effects do not occur as participants do not repeat conditions
•participants are less like my to guess the aim
limitation of an independents group design
• the participants who occupy the groups are not the same, the participant variables may have an effect on the DV- to deal with this the researchers must use random allocation
•less economical than repeated measures as twice as many participants would be needed to fulfil both conditions
strength of repeated measures design
•participant variables are controlled and fewer participants are needed
limitations of a repeated measures design
•order effects may occur, performance may improve (known as practice effect) or it may decline (fatigue effect), researchers use counter balancing to combat this
•participants are more likely to work out the aim of the study, so demand characteristics may feature
strengths of the matched pairs design
•may reduce participant variables, however pairs can never be matched exactly
•participants only take part in a single condition so order effects and demand characteristics are less of a problem
limitation of a matched pairs design
•matching may be time consuming and expensive
how to reduce order effects
•counterbalancing- half the participants do condition A first, half of condition B first
•randomisation- for each participant, the order in which they experience each condition is decided by chance
