INTRODUCTION TO STATISTICAL MODELLING IN R

Chapter 4A one-way anova, and a qqnormplotThis chapter shows you how to construct a one-way analysis of variance and how todo a qqnorm-plot to assess normality of the residuals.Here is the data in the file ‘potash’: nb, you may need to do some work to get thedatafile in place before you go into R.7.62 8.00 7.938.14 8.15 7.877.76 7.73 7.747.17 7.57 7.807.46 7.68 7.21The origin of these data is lost in the mists of time; they show the strength of bundlesof cotton, for cotton grown under 5 different ‘treatments’, the treatments inquestion being amounts of potash, a fertiliser. The design of this simple agriculturalexperiment gives 3 ‘replicates’ for each treatment level, making a total of 15 observationsin all. We model the dependence of the strength on the level of potash.This is what you should do.y