Graphing the Regression Line
Graph regression lines in Grade 10 statistics. Use the calculator RegEQ variable to plot the regression line over a scatter plot and visually assess how well it fits the data.
Key Concepts
Property After calculating a regression line, the calculator stores the equation in a special variable called RegEQ. To plot it, go to the Y= editor, press [VARS], navigate to 5:Statistics..., then open the EQ menu and select 1:RegEQ. This pastes the equation into Y₁ so you can graph it over your data points without manual entry.
In the [Y=] editor: Press [VARS] → [5:Statistics...] → [EQ] → [1:RegEQ] to paste the equation. With the equation in Y₁, press [GRAPH] to draw the best fit line over your scatter plot. To compare lines, paste one into Y₁ and a second (like Med Med) into Y₂.
Your calculator already did the hard math! Instead of retyping the equation, just tell the Y= editor to grab the RegEQ variable. It's a fantastic shortcut that prevents typos and saves you a ton of time!
Common Questions
How do you graph a regression line on a graphing calculator?
After running LinReg, the equation is stored in RegEQ. Go to Y=, press VARS, select Statistics, then EQ and RegEQ. Enable STAT PLOT for the scatter plot, then press GRAPH to see both.
How do you assess how well the regression line fits the data?
Look at the scatter plot and regression line together. Points should be evenly distributed close to the line. The r² value quantifies fit: r² = 0.85 means 85% of variance in y is explained by x.
What is the difference between a scatter plot and a regression line?
A scatter plot shows individual data points. The regression line is the single best-fit straight line through those points, summarizing the overall trend.