6P.7—Plotting and interpreting graphs

Plot the dependent variable against the independent variable with labelled axes, units, sensible scales and uncertainty. Use a scatter plot for paired measurements and a line only when a relationship is justified.

A rate–temperature graph may rise to an optimum then fall; a straight best-fit line across the whole range would hide the biological pattern.

A graph supports interpretation by showing trend, variation, plateau, threshold and anomalies; it does not replace the data table.

A line of best fit is not proof of causation or linearity.