01
Central Tendency
Mean, median, and mode describe where the centre of your data lies. The mean is sensitive to outliers; the median is not. Use mode for discrete or categorical data.
02
Spread & Dispersion
Standard deviation, variance, IQR, and range describe how spread out your data is. Use sample variants with Bessel's correction when working with a sample, not a full population.
03
Position & Shape
Z-scores, percentiles, and skewness tell you where individual values sit and how symmetrical the distribution is. Skewness near 0 means symmetric; positive means a right tail.