experimental design Flashcards
what are independent groups
uses different pps in each experimental conditions so pps only does one condition then pps are being tested against each other
strengths of independent groups
no order effects - practise or fatigue won’t affect results
reduces demand characteristics as they only do it once - they might guess hypothesis on second time
limitations of independant groups
pps in each condition are different so we don’t know if their individual differences are influencing results
need more pps than other designs
how to deal with independant groups limitations
randomly allocate pps to conditions which theoretically distribute participant variables evenly
what are repeated measures
all pps take part in all conditions of the IV performances of the two tests are then compared
strengths of repeated measures
individual differences are controlled for as its the same pps both times no differences in age, gender or IQ
fewer pps needed
limitations of repeated measures
creates order effects e.g pps may recall more words second Time if it was a memory test
creates practise and fatigue effects
how to deal with limitations of repeated measures
researcher should use two different tests to reduce practise effects
use counterbalancing to deal with order effects
what is counterbalancing
attempt to control order effects in repeated measures design
what is counterbalancing method 1
in group 1 each pps does condition A (morning) then B (afternoon)
in group 2 each pps does condition B (afternoon) then A (morning)
what is counterbalancing method 2
group 1 does all conditions twice so ABBA ( morning, afternoon, afternoon and morning) then scores are compared on morning then on afternoon
what are matched pairs
two different groups of pps each participant in group A is matched with someone in group B based on gender/IQ matching characteristics must be relevant to study
strengths of matched pairs
less confounding variables caused by individual differences
no order effects or demand characteristics as groups are even
limitations of matched pairs
matching pps is very difficult
individual differences are only reduced not eliminated
how to deal with limitations of matched pairs
conduct a pilot study to identify key variables that are important when matching
