## Density of the Chi-square distribution for different
## parameter values (degrees of freedom)
curve(dchisq(x, df=1), .05, 5,
      xlab = "",
      ylab = "Chi-square density, df=1"
      )
curve(dchisq(x, df=2), .05, 5,
      xlab = "",
      ylab = "Chi-square density, df=2"
      )
curve(dchisq(x, df=5), .2, 20,
      xlab = "",
      ylab = "Chi-square density, df=5"
      )
curve(dchisq(x, df=10), .2, 20,
      xlab = "",
        ylab = "Chi-square density, df=10"
      )