Dawnbridge

Casio fx-CG50 field manual for IB Math

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22

Linear regression and r

All courses

Enter paired data into two table columns, enable the calculator's correlation diagnostics, run linear regression, and read the regression equation and r.

Goal

Find the least-squares regression line and correlation coefficient for ​(1,2.1),  ​(2,2.9),  ​(3,3.7),  ​(4,4.6),  ​(5,5.1).

1

From the MAIN MENU, open Statistics. If you're already inside another app, press first to get back to MAIN MENU.

2

Enter the ​x​-values 1, 2, 3, 4, 5 in List 1 and the ​y​-values 2.1, 2.9, 3.7, 4.6, 5.1 in List 2. Press after each entry.

RadNorm2
d/cReal
List 1List 2List 3List 4SUB112.1222.9333.7444.6555.1
GRAPHCALCTESTINTRDIST▷
3

Press (CALC), then (SET), and set 2Var XList = List1, 2Var YList = List2 and 2Var Freq = 1. Press to return. There is no correlation setting to switch on: linear regression always reports ​r.

4

Press (REG), then (X), then (ax+b). The Casio displays the line coefficients and the correlation coefficient.

RadNorm2
d/cReal
LinearReg(ax+b)
a=0.77
b=1.37
r=0.99672722
r²=0.99346515
MSe=0.013
y=ax+b
COPY
Result

The regression line is ​y≈1.37+0.77x, and the correlation coefficient is ​r≈0.997.

Your turn

Work each one on your calculator, then check the answer.

  1. 1

    Find the regression line and ​r​ for ​(1,3.8),  ​(2,5.1),  ​(3,6.4),  ​(4,8.2),  ​(5,9.3),  ​(6,10.9).

  2. 2

    Find the regression line and ​r​ for ​(1,9.2),  ​(2,7.9),  ​(3,6.1),  ​(4,4.8),  ​(5,3.5).

  3. 3

    Find the regression line and ​r​ for ​(2,3.1),  ​(4,4.9),  ​(6,7.2),  ​(8,8.8),  ​(10,11.3).