TI-84 Statistics: 1-Var Stats and Regression

The TI-84 is a strong statistics tool. It computes means, deviations, and regressions in seconds. This guide covers statistics on ti 84 calculators from data entry to linear regression.

One habit first: clear old lists before new data. Stale numbers from last week silently corrupt new results. In the list editor, arrow to the list name and press [CLEAR][ENTER].

Enter Data into Lists

All statistics start with lists. The calculator stores data in L1, L2, and more.

  1. Press [STAT], then press [ENTER] for 1:Edit.
  2. Type your data values into L1, pressing [ENTER] after each one.
  3. If you have paired data, type the second set into L2.

Made a typo? Arrow to the value, type the fix, and press [ENTER].

Sort Data Before You Start

Sorted lists make patterns clear. Sorting takes two keys.

  1. Press [STAT], arrow to 2:SortA(.
  2. Type L1 ([2nd][1]) and press [ENTER].

Your data now runs low to high. Medians and quartiles are easier to spot by hand.

Run 1-Var Stats

One-variable statistics give you the mean, standard deviation, min, max, and quartiles.

  1. Press [STAT], arrow right to CALC, and press [ENTER] for 1:1-Var Stats.
  2. If your data is in L1, just press [ENTER]. The calculator assumes L1.
  3. For another list, type 2nd → [1] (or [2] for L2) before pressing [ENTER].

The results screen shows x̄ (mean) and n (count). Arrow down for quartiles. Note Sx versus σx: Sx is the sample standard deviation, σx the population one. Stats classes almost always want Sx.

Do Linear Regression

Regression finds the line of best fit for paired data. Put x-values in L1 and y-values in L2 first.

  1. Press [STAT], arrow to CALC, and choose 4:LinReg(ax+b).
  2. Press [ENTER] with Xlist:L1 and Ylist:L2. Store the equation in Y1 if you want the graph.
  3. Press [ENTER]. The screen shows a, b, and r².

The r² value tells you how well the line fits. Closer to 1 means a better fit. Press [GRAPH] to see the line through your data points.

normalCDF vs invNorm: Don’t Mix Them Up

This mix-up costs students the most points. The rule is simple.

Use normalCDF when you have values and want a probability. Example: the chance a score falls between 70 and 90.

Use invNorm when you have a probability and want the value. Example: the score that marks the top 10%.

Both live under [2nd][VARS] (DISTR). For normalCDF, type normalcdf(lower, upper, mean, SD). Use -1E99 for negative infinity. For invNorm, type invNorm(area, mean, SD). Watch percentile wording: “top 10%” means the 90th percentile.

Draw a Box Plot

Box plots are a core part of statistics on ti 84 exams. Your data must be in L1 first.

  1. Press [2nd][Y=] for STAT PLOT.
  2. Turn Plot1 ON and pick the box plot icon.
  3. Set Xlist to L1.
  4. Press [ZOOM], then 9:ZoomStat.

The calculator draws the plot with quartiles marked. Use [TRACE] and arrows to read each value.

Run a Hypothesis Test

The TESTS menu handles z-tests, t-tests, and more. It also computes test statistics.

  1. Press [STAT], arrow right twice to TESTS.
  2. Pick your test, such as 2:T-Test or 5:1-PropZTest.
  3. Choose Stats (summary) or Data (lists), fill in the values, and select Calculate.

The output shows the test statistic and p-value. Compare the p-value to your alpha level to decide. The calculator cannot interpret the result for you. Know what “reject” means before the exam.

Frequently Asked Questions

How do I clear lists before new data?

In the list editor, arrow up to the list name (L1) and press [CLEAR], then [ENTER]. The list empties.

What is the difference between Sx and σx?

Sx is the sample standard deviation. σx is the population standard deviation. Stats classes usually want Sx.

How do I get r (not just r²) in regression?

Press [2nd][0] for CATALOG, scroll to DiagnosticOn, and press [ENTER] twice. Run LinReg again to see r.

Why do I get ERR: DATA TYPE with normalcdf?

The DISTR functions take numbers only, not lists. Type normalcdf(-1E99, 200, 100, 15), not normalcdf with L1 inside.

Can I plot the data points?

Yes. Press [2nd][Y=] for STAT PLOT, turn Plot1 on, and choose the scatter plot type. Then press [ZOOM] → 9:ZoomStat.

Do these steps work on the free online TI-84?

Yes. Every statistics function here works on our free TI-84 Plus CE emulator in your browser.