Test for Effectiveness of Appetite-Reducing Drug Essay

Test for Effectiveness of Appetite-Reducing Drug - Essay Example Describe the four different threats to internal validity [intact groups, extraneous variables, subject loss, and expectancies]. How do these threats apply to the following study? There are four threats to internal validity in experiments. The assignment of intact groups, rather than individuals, compromises the randomness of the sample and therefore skews the results. The presence of extraneous variables confounds the findings and renders them uninterpretable. Subject loss due to any one particular condition more than others renders some subjects unable to continue. Finally expectations held by either the subjects or experimenters, or both, tend to affect their conduct during the experiment which may affect the results. Internal validity is compromised in this experiment. The biggest threat to the experiment’s internal validity is the presence of expectations of the experimenter which may create a bias in the results obtained. In the given situation, the experimenter is not bl ind as to who among the students are given the placebo, the tested drug, and the new experimental drug. While it is mentioned that the experimenter is determined to remain unbiased, this is not enough as psychological bias may be unintended but nevertheless present in the results. External validity does not seem to be an issue here, because the sample chosen was randomly selected and therefore may be assumed to represent the relevant population of KU students. Also, since all groups are given the same examination that covers the contents of the full ten week course, and no other variable had been varied except the test variable (the experimental drug), then chance variables... The objective of the experiment to be designed should determine whether or not the experimental drug is effective in reducing the appetite of the individual ingesting it. Â   The procedure would involve administering the drug to the test group and monitoring the progress in the food consumption (proxied by the relative change in weight of the subjects) Â  of the test group against a control group. Â  In order for the control group to be blind to which group they belonged, they will be given placebos which are known to have no effects on the appetite. The experimental method to be used would be the independent group design, the alternative to the repeated measures design group. Â  Repeated measures design is not applicable to this assignment because for repeated measures, the same subjects repeatedly undergo all the procedures at intervals, and reactions to the test condition are observed when the condition is applied and when it is withdrawn. Â  This will not do because the succ essful administration of the drug would presumably include a weight loss, and repeated treatment (to reduce appetite) may reasonably cause a drop in weight. The loss in weight would be a permanent change to the subject, whether as a result of the treatment or not, and withdrawal of the treatment does not necessarily cause a reversal to pre-treatment conditions. It therefore defies the reason for the alternate application and removal of treatment. Â  Furthermore, it is ethically questionable to withdraw a treatment.