requires a relatively beliefs about • smaller number of experimental participants when procedures can be compared with more difficult to experimental designs as control due to cues same participants are in from experiencing all conditions different conditions participant attrition • pairs of participants ensures each difficulty identifying • • • are matched on the condition/group is fairly all relevant variables basis of relevant equivalent in spread of (to be matched) personal relevant personal practical problems, • characteristics that characteristics that can e.g. time-consuming can influence the influence the DV to identify and recruit DV, then one participant attrition less participants who are • member of each likely sufficiently in the pair is randomly variable, pre-testing allocated to may be required and different can lead to order conditions/groups effects requiring control each participant is no effects across less control over • • • randomly allocated conditions to control participant to either the characteristics than participant attrition less • experimental or repeated-measures likely control group and is and in one group only often need a larger • group of participants in order to lessen any differences between groups 2 For each of the following extraneous or potential confounding variables, rank the three experimental designs from 1 to 3 to indicate the extent to which the design controls the variable, as compared to the other designs. A ranking of 1 indicates greatest control and a ranking of 3 indicates least control. If appropriate, more than one design may be given the same ranking. Explain your choice of rankings. Variables Repeated-measures Matched-participants Independent-groups
• requires a relatively smaller number of participants when compared with experimental designs as same participants are in all conditions beliefs about experimental procedures can be more difficult to control due to cues from experiencing different conditions • participant attrition • pairs of participants are matched on the basis of relevant personal characteristics that can influence the DV, then one member of each pair is randomly allocated to different conditions/groups • ensures each condition/group is fairly equivalent in spread of relevant personal characteristics that can influence the DV • participant attrition less likely • difficulty identifying all relevant variables (to be matched) • practical problems, e.g. time-consuming to identify and recruit participants who are sufficiently in the variable, pre-testing may be required and can lead to order effects requiring control • each participant is randomly allocated to either the experimental or control group and is in one group only • no effects across conditions to control • participant attrition less likely • less control over participant characteristics than repeated-measures and • often need a larger group of participants in order to lessen any differences between groups 2 For each of the following extraneous or potential confounding variables, rank the three experimental designs from 1 to 3 to indicate the extent to which the design controls the variable, as compared to the other designs. A ranking of 1 indicates greatest control and a ranking of 3 indicates least control. If appropriate, more than one design may be given the same ranking. Explain your choice of rankings. Variables Repeated-measures Matched-participants Independent-groups
ch1la_answerguide.docx