E-Code

How to graph a line of best fit on a TI-84 Plus CE or TI-84 Plus

By E-Code · updated

Press STAT ▶ CALC 4 (LinReg(ax+b)), ▼ to Store RegEQ, press VARS ▶ Y-VARS, ENTER, ENTER for Y1, then ▼ to Calculate and ENTER. Turn on 2nd STAT PLOT 1 (ENTER on On) and press ZOOM 9 (ZoomStat): the data and the line are drawn together.

Before you start

Type 1, 2, 3, 4, 5 into L1 and 2, 4, 5, 4, 5 into L2 first (STAT, ENTER), then 2nd QUIT.

STAT ENTER 1 ENTER 2 ENTER 3 ENTER 4 ENTER 5 ENTER ▶ 2 ENTER 4 ENTER 5 ENTER 4 ENTER 5 ENTER 2nd MODE

Step by step

  1. Open STAT. STAT Press STAT. Your data is already in L1 and L2.
  2. The CALC tab. ▶ Press ▶ to CALC.
  3. Pick LinReg(ax+b). 4 Press 4. The wizard opens with Xlist L1 and Ylist L2.
  4. Go down to Store RegEQ. ▼ ▼ ▼ Press ▼ three times to Store RegEQ: where the line's equation goes.
  5. Open VARS. VARS Press VARS.
  6. The Y-VARS tab. ▶ Press ▶ to Y-VARS: the Y= functions.
  7. Pick Function. ENTER Press ENTER for Function.
  8. Pick Y1. ENTER Press ENTER for Y1. It goes into Store RegEQ.
  9. Go down to Calculate. ▼ Press ▼ to Calculate.
  10. Calculate. ENTER Press ENTER. The line is worked out and stored in Y1.
  11. See it in Y=. Y= Press Y=. Y1 now holds the line of best fit.
  12. Open STAT PLOT. 2nd Y= Press 2nd, then Y= (STAT PLOT), to show the data points too.
  13. Open Plot1. 1 Press 1. Plot1 draws Xlist L1 against Ylist L2 as a scatter plot.
  14. Turn it on. ENTER Press ENTER with the cursor on On.
  15. Open ZOOM. ZOOM Press ZOOM. Item 9 is ZoomStat.
  16. ZoomStat. 9 Press 9. ZoomStat sets a window that fits all your data, then draws.
  17. Data and line together. The dots are your data and the line is y = .6x + 2.2, running through the middle of them.

What the screen shows

The dots are your data and the line is y = .6x + 2.2, running through the middle of them.

Look for ZStandard on the screen.

Try it with the keys lit up

This guide is one of E-Code's Learn lessons. Open it on E-Code's TI-84 calculator and each key lights up in turn as you press it.

Try “Graph a line of best fit” on the TI-84 calculator

Related

Statistics programs for the TI-84 Plus CE:

All TI-84 statistics guides · All TI-84 guides · All calculator guides