Introductory Biostatistics
tory variables who survive tot. In other words, survival condition and reason of loss are independent; under this assumption, th ...
The explanation could be simple, as follows: (1)di=niis the proportion (or estimated probability of having an event in the inter ...
to obtainSS^ðtÞ, multiply all values in column (4) up to and includingt. From Table 11.1, we have, for example: 7-week survival ...
Pool data from two samples together and let t 1 <t 2 <<tm madan 1 þn 2 be the distinct times with at least one eve ...
Var 0 ðd 1 iÞ¼ n 1 in 2 iaidi ni^2 ðni 1 Þ the formula we used in the Mantel–Haenszel method in Chapter 6. After constructing a ...
fore, by default, is more sensitive to exposures with a constant relative risk (the proportional hazards e¤ect; in fact, we have ...
Note:An SAS program would include these instructions: PROC LIFETEST METHOD = KM; TIME WEEKS*RELAPSE(0); STRATA DRUG; where KM st ...
morphologic characteristic of white cells (Table 11.3). Patients termed AG positive were identified by the presence of Auer rods ...
bis anunknownregression coe‰cient. The estimation ofband subsequent analyses are performed as follows. Denote the ordered distin ...
lðt;nonexposedÞ¼l 0 ðtÞ lðt;exposedÞ¼l 0 ðtÞeb so that the ratio eb¼ lðt;exposedÞ lðt;nonexposedÞ represents the relative risk ( ...
then lðt;nonexposedÞ¼l 0 ðtÞeb lðt;exposedÞ¼l 0 ðtÞeb so that RR¼ lðt;exposedÞ lðt;nonexposedÞ ¼e^2 b and its 95% confidence in ...
The results above are di¤erent for two di¤erent choices ofX, and this causes an obvious problem of choosing an appropriate measu ...
11.4.1 Proportional Hazards Model with Several Covariates Suppose that we want to considerkcovariates simultaneously. The propor ...
These results are necessary in an e¤ort to identify important prognostic or risk factors. Of course, before such analyses are do ...
Three likelihood-based statistics can be used to test thisglobalnull hypoth- esis; each has a symptotic chi-square distribution ...
As with thez testabove, thismultiple contribution procedureis very useful for assessing the importance of potential explanatory ...
clinically important itself, but adjustments are still needed in e¤orts to investi- gate other covariates. We define the hazard ...
is almost significant at the 5% levelðp¼ 0 : 0732 Þ; that is, the presence of the morphologic characteristic modifies substantia ...
L¼ Ym i¼ 1 PrðdijRi;diÞ ¼ Ym i¼ 1 expð Pk j¼ 1 bjsjiÞ P Ciexpð Pk j¼ 1 bjsjuÞ where sji¼ X lADi xjl sju¼ X lADu xjl DuACi andRii ...
time-dependent covariates: those that can be defined by a mathematical equa- tion (external) and those measured directly from pa ...
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