A university medical center urology group was interested in the association between prostate-specific antigen (PSA) and the Gleason score (pathologically determined grade of disease, coded 1, 2, or 3, with higher scores indicating worse prognosis).Data were collected on 97 men who were about to undergo radical prostatectomies. (4 points for each sub-question)

1. A scatter plot of the PSA level (in mg/ml) and the Gleason score is shown below. Does the variability of the PSA level within each factor level of Gleason score appear to be approximately the same for all factor levels?