Refer to the data of Exercise 30 and compute a 95% CI for the difference between true av...

Refer to the data of Exercise 30 and compute a 95% CI for the difference between true average concentrations for treatments II and III.

Reference exercise 30

The given data on phosphorus concentration in topsoil for four different soil treatments appeared in the article “Fertilisers for Lotus and Clover Establishment on a Sequence of Acid Soils on the East Otago Uplands” (N. Zeal. J. of Exptl. Ag., 1984: 119–129). Use a distribution-free procedure to test the null hypothesis of no difference in true mean phosphorus concentration (mg/g) for the four soil treatments.