How to Read a Lottery Frequency Heatmap Without Fooling Yourself

A frequency heatmap colours each number by how often it appeared. The human visual system is extremely good at finding clusters — including clusters that are not there.

Always anchor to the expected count

Compute expected count as (draws × numbers per draw) ÷ pool size. Colour the map by deviation from that expected value, not by raw count. A map coloured by raw count will always look dramatic.

Use a significance band

For a large sample, the standard deviation of a number's count is approximately the square root of the expected count. Shade anything within two standard deviations as neutral. On most real lottery windows, that leaves almost the whole board neutral — which is the correct, if unexciting, conclusion.