Introductory Biostatistics
Each of these goodness-of-fit statistics devided by the appropriate degrees of freedom, called thescaled Pearson chi-squareandsc ...
Note: An SAS program would include these instructions: INPUT DOSE N TOXIC; PROC LOGISTIC DESCENDING; MODEL NODES TOXIC/N = DOSE/ ...
actions). Therefore, to provide a more comprehensive analysis, it is very desir- able to consider a large number of factors and ...
exp½bb^iG 1 :96 SEðbb^iÞ These results are necessary in the e¤ort to identify important risk factors for the binary outcome. Of ...
This phenomenon is callede¤ect modification(i.e., one factor modifies the e¤ect of the other. The cross-product termx 1 x 2 is c ...
finding a satisfactory interpretation for thecurvature e¤ect coe‰cientb 2 is not easy. Perhaps a rather interesting application ...
Both statistics are provided by most standard computer programs, such as SAS, and they are asymptotically equivalent, yielding i ...
wherebb^iis the corresponding estimated regression coe‰cient and SEðbb^iÞis the estimate of the standard error ofbb^i, both of w ...
Contribution of a Group of Variables This testing procedure addresses the more general problem of assessing the additional contr ...
and that the e¤ect of acid phosphatase on the response may be somewhat stronger for a certain combination of levels of the other ...
Test for the significance of the factor selected in step 2 and determine, according to a certain predetermined criterion, wheth ...
Step 1:Variable ‘‘x-ray’’ is entered. Analysis of variables not in the model is shown in Table 9.9. Step 2:Variable ‘‘stage’’ ...
Step 3:Variable ‘‘acid’’ is entered. Analysis of variables in the model is shown in Table 9.12. None of the variables are remov ...
We can determine theoptimalcut point, which is nearest to the upper left cornerð 0 ; 1 Þ. This corner corresponds to 100% sensi ...
the association between the response and the set of independent variables considered together; for example, withR^2 ¼1, we can p ...
Fit a simple logistic linear regression model to each factor, one at a time. Select the most important factor defined as the on ...
PrðY¼ 1 ;X¼xÞ PrðY¼ 0 ;X¼xÞ ¼ PrðY¼ 1 Þ PrðY¼ 0 Þ PrðX¼x;Y¼ 1 Þ PrðX¼x;Y¼ 0 Þ On the right-hand side, the ratio of prior probabi ...
EXERCISE 9.1 Radioactive radon is an inert gas that can migrate from soil and rock and accumulate in enclosed areas such as unde ...
TABLE E9.1DISEASE GENDER RACE RADON MSMOKE MDRINK FSMOKE FDRINK DOWNS 1211 7111 21 1218 1220 2 22181 2122 2111 2020 2 1114 20202 ...
1129 2020 1 1211 51112 1 2211 72012 1 1119 2012 1 2111 5202 01 1111 0111 11 2111 1122 01 1218 20201 1111 4122 02 2211 4121 22 12 ...
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