Macular degeneration is the most common cause of blindness in people older than 60 years. One variable thought to be related to a type of inflammation associated with this disease is level of a substance called soluble Fas ligand (sFasL) in the blood. The accompanying table contains representative data on x = sFasL level for 10 patients with age-related macular degeneration. These data are consistent with summary quantities and descriptions of the data given in the paper "Associations of PlasmaSoluble Fas Ligand with Aging and Age-Related Macular Degeneration" (Investigative Ophthalmology & Visual Science [2008]: 1345-1349). The authors of the paper noted that the distribution of sFasL level was skewed and recommended a cube-root transformation. The cube-root values and the normal scores for a sample size of 10 are also given in the accompanying table.
a. Construct a normal probability plot using the untransformed data.
b. Does the normal probability plot appear linear or curved?
c. Construct a normal probability plot using the transformed data. Does the normal probability plot appear more nearly linear than the plot for the untransformed data?