TY - CHAP M1 - Book, Section TI - Chapter 11. How to Analyze Survival Data A1 - Glantz, Stanton A. Y1 - 2012 N1 - T2 - Primer of Biostatistics, 7e AB - All the methods that we have discussed so far require “complete” observations, in the sense that we know the outcome of the treatment or intervention we are studying. For example, in Chapter 5 we considered a study that compared the rate of filing advance directives in people who received in-person counseling or written instructions (Table 5-1). We compared these two groups of people by computing the expected pattern of thrombus formation in each of the two comparison groups under the null hypothesis that there was no difference in the rate of thrombus formation in the two treatment groups, then used the chi-square test statistic to examine how closely the observed pattern in the data matched the expected pattern under the null hypothesis of no treatment effect. The resulting value of χ2 was “big,” so we rejected the null hypothesis of no treatment effect and concluded that aspirin reduced the risk of thrombus formation. In this study we knew the outcome in all the people in the study after a fixed length of time following treatment. Indeed, in all the methods we have considered in this book so far, we knew the outcome of the variable under study for all the individuals in the study being analyzed. There are, however, situations, in which we do not know the ultimate outcome for all the individuals in the study because the study ended before the final outcome had been observed in all the study subjects or because the outcome in some of the individuals is not known.* In addition, it would be desirable to take into account the outcomes in people who were enrolled in the study for varying lengths of follow-up that allows for the fact that the more time that passes after treatment the more likely it is that there would be the outcome of interest. We now turn our attention to developing procedures for such data. SN - PB - The McGraw-Hill Companies CY - New York, NY Y2 - 2024/03/28 UR - accessanesthesiology.mhmedical.com/content.aspx?aid=57419766 ER -