One important variable to consider in trading stock is the daily volume. Volume is measured in number of shares traded in the stock. Stocks with lower volume tend to have more variability in the stock price. A stock analyst believes the median number of shares traded in Walgreens Boots Alliance (WBA) stock is greater than that in McDonalds (MCD). Because national news can play a role in volume of stock traded, the analyst records the volume (in millions of shares) for each of the two stocks on the same day for 14 randomly selected trading days. The results are in Table 5. Test the analyst's belief at the \(\alpha=0.05\) level of significance. Note: A normal probability plot indicates the differenced data do not come from a population that is normally distributed.

Approach This is matched-pairs data since the volume is measured on the same day for each stock. The differenced data are not normal, so we cannot use Student's \(t\)-distribution as a model. Therefore, we use Wilcoxon's matched-pairs signed-ranks test.

Table 5 Day WBA MCD Day WBA MCD 1 8.9 8.5 8 6.0 4.7 2. 6.3 7.6 9 15.6 9.0 3. 6.2 8.3 10 5.2 6.0 4 7.2 10.4 11 6.3 5.6 5 2.8 2.5 12 10.1 5.0 6 3.3 2.6 13 4.0 4.4 7 23.6 3.5 14 8.4 5.6