A study of the effects of a chemical additive on soil acidity recorded the soil acidity of eight plots of land before and after the application of the additive.The results
Were: The test value for the sign test is:
A)1
B)2

Question

A study of the effects of a chemical additive on soil acidity recorded the soil acidity of eight plots of land before and after the application of the additive.The results
Were:  The test value for the sign test is:
A)1 
B)2

Quizplus · Accepted Answer

The sign test is used to determine whether the values in one sample are generally larger or smaller than the values in another sample. In this case, we are comparing the before and after soil acidity values of each plot. If the additive has no effect on soil acidity, we would expect half of the plots to have higher acidity after the application and half to have lower acidity. We can determine this by counting the number of positive (+) and negative (-) differences between the before and after values. In this case, there are 3 positive differences and 5 negative differences, indicating that the additive may have decreased soil acidity. The test value for the sign test is the smaller of the two values: the number of positive differences or the number of negative differences. Therefore, the test value is 3, which is less than the critical value (4 for n=8 at the 0.05 level). We can reject the null hypothesis that the additive has no effect on soil acidity. The correct choice is A.

A Study of the Effects of a Chemical Additive on Soil