The authors present an undergraduate experiment laboratory project involving lecithin which integrates these key components of thin layer and column chromatography.
One of the most consistent criticisms of expectancy theory research for the prediction of effort is that it has not been tested using the within-subjects choice model that the theory requires. The choice model proposed by the theory generates a motivational force score (MFS) for each of several effort levels for each subject and predicts that each will choose the level of effort which has the highest MFS for that subject. This study operationalizes the choice model and compares it with a difference model (derived from subtracting the MFS for low effort from the MFS for high effort) and a singlealternative model (MFS for high effort only). Subjects were 74 undergraduates who estimated valences and expectancies for the outcomes of six general student activities. The difference model, not the choice model, was generally the best predictor, while the single-alternative model predicted least well. Within-subjects predictions were of greater magnitude than between-subjects predictions. The results indicated that sufficiently designed future studies should gather data for three levels of effort (high, medium, and low) and then compare the models to determine the most effective predictor for that particular situation. While expectancy theory is the most widely accepted theory of motivation in contemporary industrial/organizational psychology, its empirical support has not been particularly strong. One reason could be that studies have used between-rather than within-subjects designs that are not consistent with the intended theoretical formulation (Mitchell, 1974). A withinsubjects approach compares a given subject's attitudes with other attitudes of that same subject, while a between-subjects approach compares one subject's attitudes with attitudes of other subjects for similar outcomes. Unfortunately, there has been no consistent approach to the construction of expectancy theory research. Most of the arguments given for using within-subjects research have referred to how the motivational force scores are measured and computed. Three alternative methods for measuring motivational force have or could be used in both within-and between-subjects studies.
A laboratory exercise in the determination of carbohydrate structures that introduces students to important aspects of science, such as designing experiments, making observations, and testing hypotheses.
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