Data points cluster tightly around a line rising from left to right. High positive association.
Points show an upward trend, but are highly scattered. Pearson r is positive but moderate.
Points cluster tightly around a line falling from left to right. High negative association.
Points appear as a random cloud with no discernible linear slope. Pearson r is close to 0.
A strong quadratic relationship exists, but because it is symmetric, Pearson r is close to 0! Correlation only measures linear trends.
A single unusual data point (outlier) dramatically drags down the correlation coefficient.
