What is the line of best fit in a scatter plot?

• A. The line drawn in a scatter plot to fit most of the dots and shows the relationship between the two sets of data
• B. The exact line passing through every data point
• C. A vertical line indicating independence
• D. A line of best fit is not used in scatter plots

Answer: (C)

The line of best fit captures the overall relationship between the two variables in a scatter plot. It’s drawn so that it best represents the pattern of the data, typically by minimizing the vertical distances from the points to the line. This line shows whether the variables tend to increase together (upward slope), decrease together (downward slope), or if there’s little relation (a flat line). It doesn’t have to pass through every point because data have variability and measurement error. A vertical line wouldn’t reveal how y changes with x, so it isn’t the line of best fit. This line is useful for making predictions: you can estimate a y-value for a given x by using the line.