Opion produced "buzz" scores for a number of stocks on the major United States indices. A buzz score was a combination of the total volume of postings to a number of Internet message boards and the credibility of those doing the posting. Opion claimed that rapid changes in buzz for a stock represented unusual activity or indicated possible trends. Opion's challenge, was scaling their buzz scores in such a way that the baseline or typical level of buzz would not influence the interpretation of a large change in buzz. This case can be used to introduce the concepts of variability, confidence limits and control limits.
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