2.4.1—Data representation

Data representation turns observations into a table, chart or graph so that a reader can see values, comparisons and patterns. The choice depends on whether the variables are categorical, discrete, continuous or ordered.

Label axes, units and categories, and preserve a scale that does not exaggerate differences. A display summarises evidence; it does not create a causal relationship or repair biased sampling.

A bar chart can compare counts in separate categories, while a histogram groups continuous values into intervals. A line graph is useful for change across an ordered variable, but joining unrelated categories implies a false sequence.

A polished graph is not automatically valid. Check what each mark represents, whether the scale is honest, and whether the display hides missing data or unequal group sizes.