Within-Groups Experiments Flashcards
what causes participants score on the DV to differ from each other
-IV(if there is an effect
-Random error
-Systematic error
what is the only design that mesures and separets Systematic Error ?
Repeated Measure design
random error
-misreading/misunderstanding question
-time of day
-recording error
t-hreatns reliability
systemetic error
-systematically decrease or increase scores on DV
-Participants’response biases(upper vs lower scale end)
-individual differences
ex:reaction time
math ability
threatens construct validity
how can we measure and separete systemetic error
repeted meausre design
out of all the variability in the DV score what proportion is attributable to the iv ?
The more random variability in DV, the harder
it is to detect the effect of the IV.
Separating out (i.e. controlling or removing)
variability from systematic error allows the
impact of the IV to be more obvious.
benefits repeted measure design
-can help us identify the effect of the IV on the DV
-Identifies some of the random error variability in the DV
scores to be systematic
-Remove systematic error from ratio
how to choose
independent group vs repeted mesure
depends on:
-strenght and permanance of experimental condition
ex : knee surgery
-external validity
- do people encouter repeted mesures in everday life
-wine testing vs wine at home
-nature of IV and DV
matched pair
an experimental design where participants are matched pairs based on important, shared characteristics before they are random assign into groups
used when u dont have enouth people
to make sure the two conditions are the same (equaly disparsed)
pre test design
a pre test is done before the experiment to make sure participants of both conditions have equal level of construct
post test design
is the samething as pretest but done after the experiment had occured
pros
counter small sample design
to select appropriate participants
if one participant drop out of the study make sure who remain are not different between condition
stop -midterm 1
