Line of Best Fit Prediction
A line of best fit is used to estimate a value from a scatter plot or a linear model. In a prediction problem, you usually substitute a given value of one variable into the line equation and solve for the other variable.
Method
- Identify the line equation.
Look for a form such as (y = mx + b). Make sure you know which variable is being predicted.
- Substitute the known value.
Replace the input variable with the number given in the problem.
- Compute carefully.
Follow the order of operations and simplify your arithmetic.
- Interpret the result.
Write the predicted value with the correct variable and units if they are given.
Check your answer
- If the slope is positive, larger inputs should give larger predicted outputs.
- If the slope is negative, larger inputs should give smaller predicted outputs.
- Your result should be reasonable for the data context and not wildly outside the pattern.
Tip
If the problem gives a graph instead of an equation, use two clear points on the fitted line to estimate the slope and intercept before predicting.