A.1.7—Scatter diagrams and correlation

A scatter diagram pairs two measured variables. Direction, strength and form of the pattern describe association; they do not by themselves identify a causal mechanism.

Plot the independent variable consistently, inspect outliers and restricted ranges, and use a correlation measure only with the assumptions and data type it requires.

Light intensity and photosynthetic rate may rise together before a plateau; the pattern suggests a relationship, while temperature or CO₂ could also influence both.

No correlation does not prove no biological relationship, and correlation never rules out confounding variables.