Statistics & Probability · beginner
How to Find the Mean, Median and Mode on a TI-84
The mean and the median measure the centre of a data set in two different ways, and the TI-84 Plus and CE return both from the single command STAT ▸ CALC ▸ 1:1-Var Stats. The mean appears as x̄ on the first screen of output; the median appears as Med once you scroll down.
The mode, though, is a different matter. Learning how to find mean median mode on a TI-84 means accepting that the calculator will hand you two of the three figures and leave you to read the third off a sorted list. This page shows where each of the three lives, why the calculator treats the mode differently, and what a worked example looks like line by line.
Get the mean and median from 1-Var Stats
Type the values into L1 using STAT ▸ 1:Edit, clearing the column first if it is not empty. Then press STAT, move to the CALC menu, and run 1:1-Var Stats on L1. The output begins with the mean and the totals.
1-Var Stats
x̄=8.571428571
Σx=60
Σx²=548
Sx=2.370453
σx=2.194613
n=7
After running 1-Var Stats on L1
x̄is the mean, calculated by adding the values and dividing byn.ΣxandΣx²are the sum and the sum of squares of the values.Sxandσxare the sample and population standard deviations.nis the number of values.
Press the down arrow and the second screen continues with minX, Q1, Med, Q3 and maxX.
↓minX=6
Q1=7
Med=8
Q3=10
maxX=13
Mean and median measure different things
The mean uses every value, so each one nudges it. The median only looks at position: with the data in order, it is the middle value, or the average of the two middle values when n is even. In the example above, the seven sorted values are 6, 7, 7, 8, 9, 10 and 13, so the fourth value, 8, is the median.
The mean comes out at 60 ÷ 7 ≈ 8.571, which is higher than the median. The single value 13 pulls the mean upward because the mean gives weight to how large a number is, while the median only cares where the number sits. When the mean is above the median, the data is skewed to the right; when it is below, the data is skewed to the left.
Why the calculator does not give the mode
The mode is the value that occurs most often, and nothing about that definition guarantees a single neat answer. A data set can have one mode, two modes, or none at all if every value appears once. A calculator cannot display a figure that might be one number, two numbers, or nothing, so the designers left the mode out of 1-Var Stats and gave you the tools to work it out instead.
For two-variable data the calculator does not have this problem, because a regression line is always a single line — the reasoning behind linear regression is a useful contrast here.
Find the mode from the sorted list
Sorting the list is the quickest reliable route. Press STAT, choose 2:SortA(, type L1 and press ENTER. The list is rewritten in ascending order in the same column, so identical values end up next to each other and are easy to count.
L1 L2 L3
6
7
7
8
9
10
13
Reading the sorted column above, the value 7 is the only one that repeats, so the mode is 7. Had 6 and 10 both appeared twice, the data would be bimodal and both would be modes. Sorting in place overwrites the original order, so if you still need the unsorted list, copy it into an empty column before you sort.
A worked example, three ways
Using the same seven values:
| Measure | Value | Where it comes from |
|---|---|---|
| Mean | 8.571 | Σx ÷ n, that is 60 ÷ 7 |
| Median | 8 | the middle value of the sorted list |
| Mode | 7 | the value that occurs most often |
The three answers differ because they answer slightly different questions: the mean describes the total shared out evenly, the median describes the middle of the queue, and the mode describes the most common value. For a beginner question that asks for “the average”, assume the mean unless the wording mentions “middle” or “most frequent”.
If 1-Var Stats fails to run, the usual cause is an empty L1, which produces ERR: INVALID DIM — see the ERR: INVALID DIM fix or the full TI-84 error codes list for the other messages. Spread around the mean is measured by the methods on our standard deviation page.
For the digital SAT, a graphing calculator such as the TI-84 is allowed on all maths questions, though the Bluebook app also supplies an on-screen graphing calculator and prohibits models with a computer algebra system. Details change occasionally, so confirm the current wording with the SAT calculator policy.
Frequently asked questions
Does the TI-84 give the mode?
No. The 1-Var Stats command returns the mean and the median, but there is no line for the mode. The mode is the value that occurs most often, so the calculator has no obvious single figure to display. You find it by sorting the list with STAT ▸ 2:SortA( and counting which value repeats.
Why are the mean and median different?
The mean uses the size of every value, so a single very large or very small number drags it away from the middle. The median only counts position, so it stays at the physical centre of the sorted list. When a value is much bigger than the rest, the mean sits above the median.
What if two values tie for the mode?
Then the data is bimodal and both values are modes. If every value appears exactly once, there is no mode at all. The calculator cannot make that judgement for you, which is one reason it leaves the mode out entirely.
How do I read the median from the 1-Var Stats screen?
The line labelled Med is the median. It sits on the second screen of output, below the values, so press the down arrow until you see Med between Q1 and Q3.
Can I sort a list without copying it first?
Sorting changes the list where it sits. STAT ▸ 2:SortA( followed by the list name sorts that list in place, in ascending order. If you need to keep the original order, store a copy in an empty column first.
Official references
Statements on this page are checked against the manufacturer or exam authority documentation below. Where an official source and this page disagree, the official source wins.