3  Variability

• Range

$$Range=\text{max}(x)-\text{min}(x)$$

• Variance

$$Variance={\sigma }^2=\frac{1}{N}\sum _{i=1}^N(x_i-\overline{x}{)}^2$$

• Standard Deviation

$$StandardDeviation=\sigma =\sqrt{\text{Variance}}$$

ct <- c(1,1,1,1,1,1,1,1,2,2,2,2,2,2,3,3,3,3,3,4,5,5,6,6,14)
mean_ct <- mean(ct)

vr <- sum((ct-mean_ct)^2)/(length(ct)-1)
sd <- sqrt(vr)