Scatterplots and Lines of Best Fit

A scatterplot shows pairs of data as points on a coordinate plane. Positive correlation: As x increases, y tends to increase (upward trend). Negative correlation: As x increases, y tends to decrease (downward trend). No correlation: No clear pattern. Strength of correlation: - Strong: Points are close to a line - Weak: Points are loosely scattered around a line Correlation ≠ Causation: Just be…

The line of best fit (regression line) is the line that best represents the trend in a scatterplot. Its equation is y = mx + b where: - m = slope (rate of change) - b = y-intercept (value when x = 0) Using the line of best fit: - Interpolation: Predict y for an x value within the data range (reliable) - Extrapolation: Predict y for an x value outside the data range (less reliable) Residual = Ac…

Example: A line of best fit for study hours (x) vs. test score (y) is y = 5x + 60. Predict the score for 6 hours of study. A student who studied 6 hours scored 85. What is the residual?