text:  # var1s.r
   
   nn <- 100
   x <- rnorm(nn, sd =2); vx <- var(x)
   chi0 <- (nn-1)*vx / 2^2
   chi0
   p.val <- 1-pchisq(chi0, nn-1)
   p.val
   ci <- c( (nn-1)*vx /qchisq(0.975, nn-1), (nn-1)*vx /qchisq(0.025, nn-1) )
   ci
  