1. There is sufficient evidence to conclude that there is a difference between the mean wear amounts of two materials based on a p-value of 0.0085 which is less than 0.01. We are 99% confident that the mean difference in wear amounts lies between 0.0121 and 0.8079. A sample size of 25 would be needed to estimate the difference to within 0.20 with 99% confidence. 2. Linear regression models were developed to predict measurements (MB, BH, BL, NH) based on year. The assumptions of each model were deemed reasonable based on an analysis of residuals and quantile-quantile plots. Each model was found to have a slope significantly different from zero based