StatisticsDescriptive Statistics

Statistics Formulas cheat sheet

8 statistics formulas on one page. Print it or save it as a PDF from the print dialog.

Mean

\bar{x} = \frac{\sum x_i}{n}

Sample variance

s^2 = \frac{\sum (x_i - \bar{x})^2}{n - 1}

z-score

z = \frac{x - \mu}{\sigma}

Standard error of a mean

SE = \frac{s}{\sqrt{n}}

Confidence interval for a mean

\bar{x} \pm t^* \frac{s}{\sqrt{n}}

Least-squares slope

b = r\frac{s_y}{s_x}

Combinations

\binom{n}{k} = \frac{n!}{k!(n - k)!}

Order does not matter.

Binomial probability

P(X = k) = \binom{n}{k}p^k(1 - p)^{n - k}

Put the formulas to work