There are three key research designs used in Psychology 1. Repeated Measures 2. Matched Participants 3. Independent Groups
Repeated Measures Design (within participants design)In a repeated measures design participants experienceboth the experimental and control groups.This is possible by conducting the experiment on twooccasions and then comparing the two results.
ADVANTAGES:1)Using the same participants means that confoundingvariables that are participant depend are eliminated.2)Allows for fewer participants to be used than withother designs.DISADVANTAGES:1) Time consuming - drop outs2) Confounding variables such as Order Effects:a) Participants may perform better on the task whendoing for a second time (practise effect).b) Participants may do worse the second time becauseof fatigue or boredom.
CounterbalancingUsed to overcome order effect.In counterbalancing, half the participantswill ﬁrst perform the task with the IVpresent (experimental condition) and thenperform the task with the IV absent (controlcondition). The other half of the participantswill experience the conditions in the reverseorder.
Matched Participants DesignEnables the researcher to identify a variable that is likelyconfounding and to eliminate the effects of this variable from theexperiment.Participants can be ranked in accordance with their scores on thisvariable and then allocated to the respective groups.
E.G. A sports coach developed a new game plan thatwould help the team reach the playoffs. He decided totest this by giving the experimental group theinstruction but not the control group. Becauseindividual skills would be a confounding variable, hedecided to ‘match’ the groups. The two highest skilledplayers will be randomly allocated to either theexperimental or control group, the third and fourthmost skilled will then be randomly allocated to eitherand so on and so forth until all players were allocatedto a group resulting in the same mean skill percentagein both groups.
Advantages: The variable on which theparticipants are ‘matched’ will not inﬂuencethe results because its effects will be thesame in the experimental and control groups.Disadvantages: It is very time consuming(and therefore expensive) to ﬁnd out thevalue of this variable for every participant.Also, if one of the pair drops out, the scoresfor the other must also be eliminated.
Independent Groups Design (between participants design)Allocates participants to theexperimental or control group at random
Advantages: The independent groups designcan be done at once and drop-outs areunlikely.Disadvantages: The procedure needs a largenumber of participants to ensure that thespread of participant variables in the samplewill match the spread in the population.
Essential Learning Activity Construct a concept map illustrating the types of research/experimental designs.* Include labelled links showing the relationshipbetween concepts* Provide an advantage and disadvantage for eachmethod