xmp06.13 {Devore6} | R Documentation

## data from Example 6.13

### Description

The `xmp06.13` data frame has 420 rows and 1 columns of the number of goals pre game scored by National Hockey League teams during the 1966-1967 season.

### Format

This data frame contains the following columns:

goals
  a numeric vector

### Source

Devore, J. L. (2003) Probability and Statistics for Engineering and the Sciences (6th ed), Duxbury

Reep, C. and Pollard, R. and Benjamin, B. (1971), ``Skill and chance in ball games'', Journal of the Royal Statistical Society, Series A, General, 134, 623–629

### Examples

    data(xmp06.13)
    attach(xmp06.13)
    table(goals)      # compare to frequency table on p. 267
    hist(goals, breaks = 0:12 - 0.5, las = 1, col = "lightgray")
    negBinom.MoM <- function(x) {
       ## method of moments estimates for negative binomial distribution
       xbar <- mean(x)
       mnSqDev <- mean((x - xbar)^2)
       c(p = xbar/mnSqDev, r = xbar^2/(mnSqDev - xbar))
    }
    print(goals.MoM <- negBinom.MoM(goals))
    ## MLE's
    optim(goals.MoM, function(x)
      -sum(dnbinom(goals, p = x[1], size = x[2], log = TRUE)))
    ## would have been better to use a transformation of p
    detach()

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