Texas Instruments TI-89, TI-92

Chapter 16: Statistics and Data Plots 263

16STATS.DOC TI-89/TI-92 Plus: Statistics and Data Plots (English) Susan Gullord Revised: 02/23/01 1:12 PM Printed: 02/23/01 2:17 PM Page 263 of 22

Statistical variables are stored as system variables. However, regCoef

and regeq are treated as a list and a function variable, respectively.

One

Var Two

Var Regressions

mean of x values üü

sum of x values GxGx

sum of xñvalues GxñGxñ

sample std. deviation of xSxSx

population std. deviation of x † sxsx

number of data points nStat nStat

mean of y values ÿ

sum of y values Gy

sum of yñvalues Gyñ

sample standard deviation of ySy

population std. deviation of y † sy

sum of xùy values Gxy

minimum of x values minX minX

maximum of x values maxX maxX

minimum of y values minY

maximum of y values maxY

1st quartile q1

median medStat

3rd quartile q3

regression equation regeq

regression coefficients (a, b, c, d, e)regCoef

correlation coefficient †† corr

coefficient of determination †† Rñ

summary points

(MedMed only) † medx1, medy1,

medx2, medy2,

medx3, medy3

† The indicated variables are calculated but are not shown on the

STAT VARS screen.

†† corr is defined for a linear regression only; Rñis defined for all

polynomial regressions.

Statistical Variables

Statistical calculation results are stored to variables. To access

these variables, type the variable name or use the VAR-LINK

screen as described in Chapter 21. All statistical variables are

cleared when you edit the data or change the calculation type.

Other conditions that clear the variables are listed on

page 260.

Calculated Variables

Tip: If regeq is 4x + 7, then

regCoef is {4 7}. To access

the “a” coefficient (the 1st

element in the list), use an

index such as regCoef[1].

Note: 1st quartile is the

median of points between

minX and medStat, and 3rd

uartile is the median of points

between medStat and maxX.

To type the character

press:

TI-89:

¥c

¤[S]

TI-92 Plus:

2 G ¤ S

To type the character

press:

TI-89:

¥c

j [S]

TI-92 Plus:

2 G S

Tip: To type a power (such

as 2 in Gxñ), ü, or ý

press

2¿

and select it from

the

Math

menu.