Читать книгу The Big R-Book - Philippe J. S. De Brouwer - Страница 277

spread – standard deviation

standard deviation

The estimator for standard deviation is:

t <- rnorm(100, mean=, sd=20) var(t) ## [1] 248.2647 sd(t) ## [1] 15.75642 sqrt(var(t)) ## [1] 15.75642 sqrt(sum((t - mean(t))^∧2)/(length(t) - 1)) ## [1] 15.75642

sd()