Experimental design

• Independent groups design: the participants only perform in one condition of the IV
• + of independent: 1) there are no order effects presented. 2) participants are less likely to guess the aims of the study (demand characteristics are eliminated)
• N- of independent: 1) no control over participant variables whereby different abilities of participants in the various conditions can cause changes to the DV. 2) You need more participants than other designs to gather the same amount of data
• Solution for independent: Random allocation solves the first limitation mentioned. this is as it ensures that each participant has the same chance of being in one condition of the IV as another
• Repeated measures: The same participants take part in all conditions of the IV
• + of repeated: 1) eliminates participant variables. 2) fewer participants needed, so not as time consuming finding and using them
• N- of repeated: 1) order effects presented e.g boredom may mean in the second condition done participants may not do as well on the task
• Solution for repeated: Counterbalancing - this is when half of the participants do conditions in one order and the other half do it in the opposite order
• Matched pairs: pairs of participants are first matched on some variable that has been found to affect the dependent variable (DV), then one member of each pair does one condition and the other does another
• + of matched: 1) no order effects. 2) demand characteristics are less of a problem
• N- of repeated: 1) time consuming and expensive to match participants. 2) a large pool of potential participants is needed which can be hard at get. 3) difficult to know which variables are appropriate for the participants to be matched.