7.93 The following figure appeared in the paper

“EDTA-Extractable Copper, Zinc, and Manganese in Soils of the Canterbury Plains” (New Zealand Journal of Agricultural Research [1984]: 207–217). A large number of topsoil samples were analyzed for manganese

(Mn), zinc (Zn), and copper (Cu), and the resulting data were summarized using histograms. The investigators transformed each data set using logarithms in an effort to obtain more symmetric distributions of values. Do you think the transformations were successful? Explain.

Transcribed Image Text:

Number of samples Number of samples 30 20 20 10 30 20 10 Untransformed data Cu Log-transformed data 0.5 1.0 1.5 2.0 -0.6 0.0 Zn 0.5 1.0 1.5 2.0 -0.6 0.0 Cu Zn 4