The data must include at least two columns of numeric or text data
The columns must have the same number of rows. You cannot include any columns with date/time data.
The sample size should be large
Although there are no formal guidelines for the amount of data needed for a heatmap, larger samples more clearly indicate patterns in the data.
The sample data should be selected randomly
In statistics, random samples are used to make generalizations, or inferences, about a population. If your data were not collected randomly, your results may not represent the population.
