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Biostatistics

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9.7 THE CORRELATION COEFFICIENT 449<br />

Height Cv Height Cv Height Cv<br />

165 17.4 176 18.2 194 18.8<br />

165 17.0 176 17.3 194 18.4<br />

165 16.3 177 17.2 194 19.0<br />

166 14.1 177 18.3 195 18.0<br />

166 14.2 179 16.4 195 18.2<br />

166 14.7 179 16.1 196 17.6<br />

166 13.9 179 17.6 196 18.3<br />

166 17.2 179 17.8 197 18.9<br />

167 16.7 179 16.1 197 19.2<br />

167 16.5 179 16.0 200 21.0<br />

167 14.7 179 16.0 200 19.2<br />

167 14.3 179 17.5 202 18.6<br />

167 14.8 179 17.5 202 18.6<br />

167 15.0 180 18.0 182 20.0<br />

167 15.5 180 17.9 190 20.0<br />

167 15.4 181 18.4 190 19.5<br />

168 17.3 181 16.4<br />

Source: Data provided courtesy of Olga Kwast-Rabben, Ph.D.<br />

Solution: The scatter diagram and least-squares regression line are shown in Figure 9.7.2.<br />

Let us assume that the investigator wishes to obtain a regression<br />

equation to use for estimating and predicting purposes. In that case the<br />

sample correlation coefficient will be obtained by the methods discussed<br />

under the regression model.<br />

Cv (units)<br />

21<br />

20<br />

19<br />

18<br />

17<br />

16<br />

15<br />

14<br />

13<br />

150 160 170 180 190 200<br />

Height (cm)<br />

FIGURE 9.7.2 Height and cervical (spine) potentials in digit I<br />

stimulation for the data described in Example 9.7.1.

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