Scatter Diagram with Regression Line
A scatter diagram plots pairs of observations as points on a graph. The least squares regression line y = a + bx minimizes the sum of squared residuals and represents the best-fit linear relationship between variables.
Real World
The UK Met Office plots daily maximum temperature against ice-cream sales across coastal resorts and draws a regression line to visualise and quantify the upward trend.
Exam Focus
When asked to 'draw' the regression line, plot two calculated points and extend through both — never estimate by eye.
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