Figure 6.1, page 83.
NOTE: Throughout this chapter and the next, the variables FFEV1 and MFEV1 have been divided by 100 before use in analyses. We have named these modified variables FFEV1a and MFEV1a, respectively.
NOTE: To get the regression line on the graph, you need to run the regression and get the predicted values. Those values are included on the plot and are connected by the line.
use https://stats.idre.ucla.edu/stat/stata/examples/pma5/lung, clear generate ffev1a = ffev1/100 regress ffev1a fheight graph twoway (scatter ffev1a fheight, msymbol(Oh)) (lfit ffev1a fheight), /// xlabel(58 62 to 78, grid) ylabel(2 2.5 to 6.5, angle(0)) /// ytitle(FFEV1)
Page 84. The descriptive statistics at the top of the page.
summarize ffev1a fheight
Variable | Obs Mean Std. Dev. Min Max
-------------+-----------------------------------------------------
ffev1a | 150 4.093267 .6507523 2.5 5.85
fheight | 150 69.26 2.779189 61 76
Page 94. The correlation in the middle of the page.
correlate fheight ffev1a
(obs=150)
| fheight ffev1a
-------------+------------------
fheight | 1.0000
ffev1a | 0.5044 1.0000
Table 6.2, page 100.
NOTE: We need to generate the residuals for use in the next figure.
regress ffev1a fheight
predict resid, resid
Source | SS df MS Number of obs = 150
-------------+------------------------------ F( 1, 148) = 50.50
Model | 16.0531702 1 16.0531702 Prob > F = 0.0000
Residual | 47.0451258 148 .317872472 R-squared = 0.2544
-------------+------------------------------ Adj R-squared = 0.2494
Total | 63.098296 149 .423478497 Root MSE = .5638
------------------------------------------------------------------------------
ffev1a | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
fheight | .1181052 .0166194 7.11 0.000 .0852633 .1509472
_cons | -4.086702 1.151979 -3.55 0.001 -6.363155 -1.81025
------------------------------------------------------------------------------
Figure 6.10, page 109. This has been skipped for now.
Figure 6.12, page 113.
NOTE: The graph produced by the qnorm command in Stata has the axes reversed from that shown in the text.
qnorm resid
