A study of the effects of a chemical additive on soil acidity recorded the acidity of eight plots of land before and after the application of the additive. The results were:

$\begin{array}{|l|l|l|l|l|l|l|l|l|}
\hline \text { Plot } & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 \
\hline \text { Before } & 10 & 8 & 9 & 7 & 8 & 6 & 9 & 11 \
\hline \text { After } & 8 & 7 & 7 & 8 & 6 & 6 & 8 & 8 \
\hline & & & & & & & & \
\hline
\end{array}$

The test value for the signed-rank test is:
A) 1
B) 2
C) 3
D) 4

Question

A study of the effects of a chemical additive on soil acidity recorded the acidity of eight plots of land before and after the application of the additive. The results were:

$\begin{array}{|l|l|l|l|l|l|l|l|l|}
\hline \text { Plot } & 1 & 2 & 3 & 4 & 5 & 6 & 7 & 8 \
\hline \text { Before } & 10 & 8 & 9 & 7 & 8 & 6 & 9 & 11 \
\hline \text { After } & 8 & 7 & 7 & 8 & 6 & 6 & 8 & 8 \
\hline & & & & & & & & \
\hline
\end{array}$

The test value for the signed-rank test is:
A) 1
B) 2
C) 3
D) 4

Quizplus · Accepted Answer

The test value for the signed-rank test is the sum of the absolute values of the differences between the before and after acidity measurements. In this case, the differences are:10 - 8 = 28 - 7 = 19 - 7 = 27 - 8 = -18 - 6 = 26 - 6 = 09 - 8 = 111 - 8 = 3The absolute values of these differences are:21212013The sum of these absolute values is 12, so the test value for the signed-rank test is 12.

A Study of the Effects of a Chemical Additive on Soil