inst/examples/sample.ratio-ex.R

In yihui/animation: A Gallery of Animations in Statistics and Utilities to Create Animations

oopt = ani.options(interval = 2, nmax = ifelse(interactive(), 50, 2))

## observe the location of the red line (closer to the population mean)
res = sample.ratio()

## absolute difference with the true mean
matplot(abs(cbind(res$ybar.ratio, res$ybar.simple) - res$Ybar), type = 'l')
legend('topleft', c('Ratio Estimation', 'Sample Average'),
       lty = 1:2, col = 1:2)

## if the ratio does not actually exist:
sample.ratio(X = rnorm(50), Y = rnorm(50))
## ratio estimation may not be better than the simple average


## HTML animation page
saveHTML({
  par(mar = c(4, 4, 1, 0.5), mgp = c(2, 1, 0))
  ani.options(interval = 2, nmax = ifelse(interactive(), 50, 2))
  sample.ratio()
}, img.name='sample.ratio',htmlfile='sample.ratio.html',
         ani.height = 400, ani.width = 500,
         title = 'Demonstration of the Ratio Estimation',
         description = c('Estimate the mean of Y, making use of the ratio',
                         'Y/X which will generally improve the estimation.'))

ani.options(oopt)