PSYC 2001 Lecture Notes - Lecture 14: Clinical Trial, Trait Theory, Latin Square
4 Nov 2016
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Another solution to deal with pretest effects is to directly assess the effect of the pretest treat the pretest as a separate (cid:498)independent variable(cid:499) Use both pretest-posttest and posttest only designs combined together in one study: solomon four-group design: if there is no effect of the pretest, posttest performance will be the same across levels of the independent variable. Independent groups design: participants participate in only one group, for example, drug trial where participants are assigned to either receiving the drug (experimental) or placebo (control) Repeated measures design: participants are in all conditions, for example, shepard: the rotation of an image and response time on how long it takes to recognize if the shape is the same shape or a nw one. Advantages: requires fewer participants (half as many in theory), extremely sensitive to statistical differences; conditions are identical because each person is their own (cid:498)control group(cid:499); necessary for longitudinal work (examining change within participants over time)
