In jeksterslabds/jeksterslabRds: Jekster's Lab Data Science and Statistics

knitr::opts_chunk$set(
  collapse = TRUE,
  comment = "#>"
)

In statistics, a $z$-score (standard score) is a signed value that indicates the number of standard deviations by which a data point is above or below the mean. A positive value indicates that the data point is above the mean. A negative value indicates that the data point is below the mean. It is calculated by subtracting the mean $\left(\mu\right)$ from the data point $\left(x\right)$ and dividing by the standard deviation $\left(\sigma = \sqrt{\sigma^2}\right)$.

\begin{equation} z = \frac{x - \mu}{\sigma} \end{equation}

The z function

The z function performs this calculation.

Example

Generating $x$

set.seed(42)
x <- rnorm(n = 1000, mean = 100, sd = 15)
hist(x)

Calculating $z$-scores

library(jeksterslabRds)
std <- z(x = x, mu = 100, sigma = 15)
hist(std, main = "Histogram of z")

jeksterslabds/jeksterslabRds documentation built on July 16, 2020, 3:41 p.m.