Guidebook
Support and Service Information Product Support
Customers in the U.S., Canada, Puerto Rico, and the Virgin Islands
For general questions, contact Texas Instruments Customer Support: phone: e-mail:
1.800.TI.CARES (1.800.842.2737) ti-cares@ti.com
For technical questions, call the Programming Assistance Group of Customer Support: phone:

1.972.917.8324

Customers outside the U.S., Canada, Puerto Rico, and the Virgin Islands
Contact TI by e-mail or visit the TI calculator home page on the World Wide Web. e-mail: Internet:
ti-cares@ti.com www.ti.com/calc

Product Service

Customers in the U.S. and Canada Only
Always contact Texas Instruments Customer Support before returning a product for service.
Customers outside the U.S. and Canada
Refer to the leaflet enclosed with this product or contact your local Texas Instruments retailer/distributor.
Other TI Products and Services
Visit the TI calculator home page on the World Wide Web.

www.ti.com/calc

B8 Reference Information
81WARR~1.DOC TI-83 Plus translation master Win Jackson Revised: 06/25/99 10:28 AM Printed: 06/25/99 1:59 PM Page 8 of 9
Warranty Information Customers in the U.S. and Canada Only
One-Year Limited Warranty for Electronic Product
This Texas Instruments (TI) electronic product warranty extends only to the original purchaser and user of the product. Warranty Duration. This TI electronic product is warranted to the original purchaser for a period of one (1) year from the original purchase date. Warranty Coverage. This TI electronic product is warranted against defective materials and construction. THIS WARRANTY IS VOID IF THE
PRODUCT HAS BEEN DAMAGED BY ACCIDENT OR UNREASONABLE USE, NEGLECT, IMPROPER SERVICE, OR OTHER CAUSES NOT ARISING OUT OF DEFECTS IN MATERIALS OR CONSTRUCTION.
Warranty Disclaimers. ANY IMPLIED WARRANTIES ARISING OUT OF THIS SALE, INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE LIMITED IN DURATION TO THE ABOVE ONE-YEAR PERIOD. TEXAS INSTRUMENTS SHALL NOT BE LIABLE FOR LOSS OF USE OF THE PRODUCT OR OTHER INCIDENTAL OR CONSEQUENTIAL COSTS, EXPENSES, OR DAMAGES INCURRED BY THE CONSUMER OR ANY OTHER USER. Some states/provinces do not allow the exclusion or limitation of implied warranties or consequential damages, so the above limitations or exclusions may not apply to you. Legal Remedies. This warranty gives you specific legal rights, and you may also have other rights that vary from state to state or province to province. Warranty Performance. During the above one (1) year warranty period, your defective product will be either repaired or replaced with a reconditioned model of an equivalent quality (at TIs option) when the product is returned, postage prepaid, to Texas Instruments Service Facility. The warranty of the repaired or replacement unit will continue for the warranty of the original unit or six (6) months, whichever is longer. Other than the postage requirement, no charge will be made for such repair and/or replacement. TI strongly recommends that you insure the product for value prior to mailing. Software. Software is licensed, not sold. TI and its licensors do not warrant that the software will be free from errors or meet your specific requirements. All software is provided AS IS. Copyright. The software and any documentation supplied with this product are protected by copyright.

All Customers Outside the U.S. and Canada
For information about the length and terms of the warranty, refer to your package and/or to the warranty statement enclosed with this product, or contact your local Texas Instruments retailer/distributor.

Reference Information B9

81WARR~1.DOC TI-83 Plus translation master Win Jackson Revised: 06/25/99 10:28 AM Printed: 06/25/99 1:59 PM Page 9 of 9

Linear Regression using the TI-81
This document describes how to use the statistics capabilities of the Texas Instruments TI-81 calculator to perform a linear regression; i.e., to find the slope and Y-intercept of a line of best-fit through a set of data. If you want to know more, refer to Chapters 7 and 3 of the TI-81 Guidebook that came with the calculator. Key presses are indicated using the same convention used by your Guidebook.

Set-Up

First, configure your calculator according to the following two figures. The key to the left of each screen describes how to get there. For each figure, make your calculator match the illustration. Remember to use () to enter -5. Next, press 2nd [DRAW] 1:ClrDraw ENTER. Finally, press existing formulas have been deleted.
and then press CLEAR until any

Entering the Data

Pt. # 11 X (C) 0.0 10.1 19.9 30.2 39.9 50.1 60.0 70.3 79.9 90.1 100.3 Y (F) 27.1 48.3 60.4 92.5 105.0 125.3 132.4 154.6 181.1 188.9 211.9
A student has obtained 11 sets of temperature readings in the Quantitative Measurements lab. These are tabulated at left. To determine the relationship between the two, you will plot F vs C and obtain an expression for the line of best fit (Note: F vs C means F goes on the Y-axis and C goes on the X-axis.) To get the data into the calculator, you enter the numbers as a sequence of (X,Y) pairs. To clear any old (X,Y) values, press 2nd [STAT] 2:ClrStat ENTER. Then, press 2nd [STAT] 1:Edit and start entering the data: 0 ENTER 27.1 ENTER 10.1 ENTER. Continue until all 11 data have been entered.

Doing the Calculation

Press 2nd [STAT] 2:LinReg ENTER. Your screen should now look like the one shown at the right. The line of best-fit has a Y-intercept of 29.783 and a slope of 1.815. Therefore, F = 1.815 C + 29.783 (remember that the equation for a straight line is y = bx + a). Finally, lets graph your result. You will plot the regression line (i.e. the line of best-fit), and then superimpose your data as a scatter plot. For VARS EQ. You should see the regression line, press Y= the first screen at right. Select 4:RegEQ to store the equation for the regression line (second screen at right). For the scatter plot, press 2nd [STAT] DRAW 2:Scatter ENTER. This last step also displays the graph.
18 Oct 95, cgrant@darkwing.uoregon.edu