Research Methods Essay Example | Topics and Well Written Essays - 1000 words - 3

Research Methods - Essay Example Subjects can either be tested once only (independent group design), or more than once or matched (repeated measures design). The advantages of the latter are that fewer participants are needed (as it may be difficult to find morbidly obese individuals), and this method can provide greater statistical power. On the other hand, there could be practice and carryover effects that would need to be minimised. In the alternative of an independent group design, it may be difficult to randomly assign the subjects and there could be large differences between individuals, which would make it difficult to make any meaningful observations. We would however have the advantage of having a control group so as to control some extraneous factors. Experimental Method Used and its Justification A repeated measures design is preferred due to the expected difficulty in obtaining the required subjects i.e. in finding morbidly obese individuals. They also reduce the effect of individual differences (Schinka, 2003:279). The second justification for a repeated measures design is the greater statistical power relative to the sample size (Amy, 1997). However, subjects will be selected at random and counterbalancing will also be used to offset any practice and carryover effects. The validity of the conclusions is threatened by factors that have either not been specified or included in the study and which could theoretically therefore influence the dependent variable.