Fit the Bradley-Terry model to Table 9.9.

a. Estimate the probability of Graf beating Sanchez, and construct a 90% confidence interval for this probability. Interpret.

b. By comparing the fit of this model and the simpler model, logit(II,,) = 0 alli and j, show that the likelihood-ratio statistic for testing Ho B = ... = Bs equals 11.5 with df = 4. Interpret.