TC3 → Stan Brown → TI-83/84/89 → TI-83/84 Lists for Paired t Test
revised 23 Dec 2011

List Operations for Paired t Test on TI-83/84

Copyright © 2003–2014 by Stan Brown, Oak Road Systems

Summary: In a paired t test, you find the difference between data pairs. That can be tedious, and it’s easy to drop a minus sign. This page shows you how to use TI-83/84 list operations to find the differences.

PersonBeforeAfter
17883
26466
37077
47174
57075
66871

Consider the data at left, which come from the example on Dabes & Janik’s Statistics Manual (1999), page 264. Heart rate is recorded for six people before and half an hour after drinking two cups of coffee. H1 is μd>0, and α=.01.

To perform the paired t test, you define the difference

d = After − Before

and then compute the differences. For this particular data set, all the differences are positive. But usually you will have a few negatives among the positives. It’s easy to overlook a minus sign when taking differences for many pairs of numbers, but of course that makes your t test completely bogus. Your TI-83/84 can help.

Store the “Before” numbers in L1 and the “After” numbers in L2. [STAT] [1]; cursor to L1 column heading, press [CLEAR] [ENTER], and enter the “Before” numbers.
 
Cursor to L2 column heading, press [CLEAR] [ENTER], and enter the “After” numbers.
You want to get the column of differences, After−Before, That’s the same as L2−L1, which is the formula for L3. Cursor to L3 column heading. Enter the formula, [2nd 2 makes L2] [] [2nd 1 makes L1] [ENTER].

TI-83/84 screen with Before and After numbers and formula for L3 TI-83/84 screen with Before and After numbers and differences after executing formula for L3 Notice that any excess numbers in L3, beyond the length of L1 and L2, are automatically removed. (The formula might be L1−L2 or L2−L1, depending on how you defined your d.)

Now you can proceed with the t test, using the data in L3.

Find sample mean and standard deviation. [STAT] [] [1] for 1-VarStats, then [2nd 3 makes L3].
Since the sample statistics are automatically pasted to the t test screen, you don’t need to copy them. Just enter the μ and the “>” from your H1. [STAT] [] [2] for T-Test
 
Enter 0 for μo. Skip past , s, and n. Enter >μo, then select CALCULATE or DRAW.

TI-83/84 screen showing sample statistics TI-83/84 screen: T-Test input TI-83/84 screen: T-Test output

How would you show your work for this problem? Here’s a sample:

“before” in L1, “after” in L2, L3=L2-L1
1-VarStats L3
T-Test inputs: μo: 0, : 4.17, s: 1.83, n: 6, μ >μo
Outputs: t = 5.5624, p = .0013

Now practice with any of the examples in your textbook.


This page is used in instruction at Tompkins Cortland Community College in Dryden, New York; it’s not an official statement of the College. Please visit www.tc3.edu/instruct/sbrown/ to report errors or ask to copy it.

For updates and new info, go to http://www.tc3.edu/instruct/sbrown/ti83/