Experimental Design: Correlating Chocolate with Mood

Experimental Design: Correlating Chocolate with Mood

A researcher hypothesizes that eating chocolate makes people happy. The researcher develops a questionnaire that includes both a question about how much chocolate one east in a week and a mood scale that measures happiness. The researcher administers the questionnaire to 100 female undergraduate students and discovers that the students who ate more chocolate did indeed have higher happiness scores on the mood scale. The researcher concludes that eating chocolate makes people happy.
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Whereas the above study concludes that there exists a correlation between the consumption of chocolate and an enhanced mood, there are several issues with the integrity of the experiment. While chocolate has long been associated with pleasure, and given that chocolate is a psychoactive food consisting of caffeine, tryptophan, theobromine and anandamide, we will refute the conclusion that chocolate acts as a pleasure enhancer and instead, consider that chocolate effects reported mood - both enhanced and depressed.
The conclusion attained by the above researcher is concerning in that correlation does not imply causation. The research conducted has given rise to the conclusion that “eating chocolate makes people happy.” This conclusion is a rather vague generalization and there is no statistical determination of the strength of the inferred correlation.   It appears that the quantity consumed has a positive correlation with the result, reflected by the statement: “those who ate more chocolate had higher scores on a mood scale.” This does not take into consideration the fact that a gross quantity can have a negative effect on mood.   Furthermore, we have little insight into any bias that the researcher might have, in terms of his professional affiliation or the sources of his funding.
Insofar as the statistics which have supported the controversial conclusion, we have determined that there were oversights in the manner in which the...