Returns on an Investor's Stock Portfolio (N = 19 Stocks) $\text { Wilcoxon Paired Data Test}$

Multiple Choice

Returns on an investor's stock portfolio (n = 19 stocks) are compared for the same stock in each of two consecutive quarters. Since the returns are not normally distributed (normality test p-values were .005 and .126 respectively) , a nonparametric test was chosen. The test results are shown below. $\text { Wilcoxon Paired Data Test}$

$\begin{array}{|l|l|l|}\hline\text { n }&\text { sum of ranks }\\\hline 19 & 247& \text {Qtr 1 }\\\hline 19 & 494& \text {Qtr 2 }\\\hline 38 & 741& \text { total}\\\hline\end{array}$


$370.50$ expected value
$34.25$ standard deviation
$- 3.59 z$
$.0003 \mathrm { p }$ -value (two-tailed) Which is the best conclusion?

A) The means are the same at ? = .01.
B) The medians are the same at ? = .01.
C) The means differ at ? = .01.
D) The medians differ at ? = .01.