NADP Data Set. The data from the National Atmospheric Deposition Program, described in Appendix C.3, also contains data on energy consumption and on energy consumption per squaremile (ECPSM) in each state. States have been subdivided into five groups based on their quintile for energy consumption per square mile as of the years 2004/2005. Does mean precipitation pH (for 2004/2005) differ by level of ECPSM? You may need to use a transformation of the form Y = −Y−k.

It may be that no transformation can be found to perfectly stabilize the variance.

If so, you may wish to investigate Welch’s method, available in most statistical packages, for adjusting the usual F test for unequal variances.

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