The dataset ex10.22, on tomato yields, is available from the package Devore6 (or in wide format from Devore7). Type This data frame gives tomato yields at four levels of salinity, as measured by...

The dataset ex10.22, on tomato yields, is available from the package Devore6 (or in wide format from Devore7). Type

This data frame gives tomato yields at four levels of salinity, as measured by electrical conductivity (EC, in nmho/cm).

(a) Obtain a scatterplot of yield against EC.

(b) Obtain side-by-side boxplots of yield for each level of EC.

(c) The third column of the data frame is a factor representing the four different levels of EC. Comment upon whether the yield data are more effectively analyzed using EC as a quantitative or qualitative factor.