Efficient Storing Of Statistical Data
In The TI-84 For AP Statistics

Adopted and extended from an article by Al Coons published in
The Statistics Teacher Network, Spring 1997, Number 47

Many AP Statistics courses utilize TI-84 calculators for analyzing data. Teachers and students often manage a large number of data sets supplied with text books, created by investigations, and downloaded from the Internet.

A Better Way To Store Data

As calculator memory has increased, an entire year's worth of data can now (2008) be stored in some calculators. In fact, all the data sets for the AP Statistics Book, Workshop Statistics and the honor precalculus book, Contempory Precalculus Through Application, can reside concurrently in a TI-84 Plus Silver Edition.

Decision needs to be made about how the data sets will be stored in the calculator. The format supplied by publishers may not be the most useful The traditional method is to provide a computer file with the data in lists for each problem. When needed, the required file is downloaded using the TI Connect software. However, this method has the following disadvantages:

• It difficult to store more than one or two data sets in the calculator at any given time since data list names may often overlap.
• If the data in the calculator is corrupted or purposely altered, there is no way to reconstruct it without reloading from either a computer or another TI calculator.
• Clearing the calculator for use in other courses or with other problems deletes data needed later.

However, these disadvantages can be overcome by:

• Storing each set of data for a given problem in a separate program. An additional advantage of storing data in programs is that it takes less storage, and then
• Storing these data programs in groups. TI groups act like folders on a computer hard drive. As described below, the TI memory can be cleared without erasing existing groups or APPS .

Storing Data In Programs In a TI-84

The following program stores distance and fare data for an airline in two lists of data named DIST and FARE. Whenever the program is executed, the data for distance and fare are created or reset.

PROGRAM:AIRFARE

SetUpEditor DIST,FARE

{576,370,612,1216,409,1502,946,998,189,787,210,737} -> DIST

{178,138,94,278,158,258,198,188,98,179,138,98} -> FARE

While a data programs can be entered directly into the calculator, there is a more efficient method. Have the data already in lists in your calculator. If you are lucky, the data can be transfered from the internet or CD-ROM that often comes with textbooks.

B. Create a new program call AIRFARE: Press PRGM. Select NEW. Press ENTER. Enter AIRFARE. Press ENTER.

C. Enter the SetUpEditor statement: Press STAT. Select SetUpEditor. Press ENTER. Press LIST. Select DIST from the list of names. Press "," (the comma key). Press LIST. Select FARE from the list of names. Press ENTER. Note: "SetUpEditor" forces only the lists DIST and FARE to be displayed in STAT EDIT after the program is executed. If they do not already exist, empty lists DIST and FARE will be created.

D. The following steps transfer the actual data from the lists to the program: Press RCL. Press LIST. Select DIST from the list of names. Rcl LDIST will appear at the bottom of the screen. Press ENTER. The actual data will be entered into the program. Press STO->. Press LIST. Select DIST from the list of names. Press ENTER

E. Repeat the process above for the list FARE.

Grouping Programs In a TI-84

Storing data for each problem in programs has great advantages. However, you will end up with an enormous number of programs. Luckily the TI-84 has a set of commands, GROUP and UNGROUP that essential create a "hard drive" on your calculator. Different groups of data can be stored together in this area. For example, all the data programs for Chapter 2 of your AP Stats Book might be stored in the group CHAPTER2. At any point, you can clear all areas of the calculator except for APPS and GROUPS by selecting the correct option of the RESET command (see below). This will free up space and make it easier to find named variable and programs. You can then UNGROUP the data programs for your next group of exercises.

A. Assume you have created two data programs for Chapter 2: AIRFARE and BACKPACK. There is also a third program, WS3, left over from other activities.

B. Store AIRFARE and BACKPACK in a GROUP called CHAPTER2: Press MEM. Select 8: GROUP... Select 1: Create New Type the name GROUP name: CHAPTER2. Select 3: Prgm.. Press ENTER by each program you wish to include in the group. A small square should appear next to each one. Select DONE.

C. Clearing the Calculator without erasing GROUPS or APPS. Assume there are many data lists and programs from previous work. Let's erase those lists and programs and then install the data programs for CHAPTER2. Note: This step will erase everything in your calculators except GROUPS and APPS. Press MEM Select 7:RESET… Select 1: ALL RAM... (NOT "ALL") Select 2: RESET Press PRGM. Note that all programs have been erased. Press LIST. Note that all lists have been erased. L1 through L6 are blank.

D. Retrieving the Data Programs for a Topic From a Group. Now that you have cleared out unwanted lists and data programs, retrieve the data programs for CHAPTER2. Press MEM Select 8: GROUP... Select UNGROUP 1: CHAPTER2. CHAPTER 2 data programs AIRFARES and BACKPACK will be loaded.. Press PRGM and select the data program you want for the problem. Now, anytime you execute the program AIRFARES, the data for that problem is created in the appropriate lists. The same holds true for the lists for BACKPACK.

Albert Coons

Buckingham Browne & Nichols School

Cambridge, MA 02138