7 statistical methods for calculating overall effect

... section we introduce several methods for this purpose A major reason for selecting these methods to present here is the availability of computer software that can perform the calculations 12.4.1 ... (7.1.8) For a continuous variable, exp(b ) represents G the increase in risk corresponding to a 1-unit increase in the variable For example, for BMI, exp (0.0255) : 1.026; that is, for every ... adjusting for age, gender, and current smoking status The SAS procedure PHREG is used with Breslow’s approximation for ties (default procedure) and three variable selection methods (forward, backward,...

Ngày tải lên: 14/08/2014, 05:21

... section we introduce several methods for this purpose A major reason for selecting these methods to present here is the availability of computer software that can perform the calculations 12.4.1 ... (7.1.8) For a continuous variable, exp(b ) represents G the increase in risk corresponding to a 1-unit increase in the variable For example, for BMI, exp (0.0255) : 1.026; that is, for every ... adjusting for age, gender, and current smoking status The SAS procedure PHREG is used with Breslow’s approximation for ties (default procedure) and three variable selection methods (forward, backward,...

Ngày tải lên: 14/08/2014, 09:22

... (1963, 1965) for dependent A".- L r TO***"-":- ,,O" - a + A*, -**"c eo%,e"t h,,",,d nes- 16.3 METHODS 16.3.1 Graphical Graphical methods are very useful aids to formal tests for trends The ... discharge-frequency weighting Methods for adjusting ambient air quality levels for meteomlogical effects an discussed by Zeldin and Meisel (1978) 16.2.4 Corrections for Flow The detection and estimation ... data in the pth group For example, in the sequence (23, 24, hace, 6, trace, 24, 24, trace, 23) we have g = 3, I, = for the tied value 23, I, = for the tied value 24, end t, = for the three trace...

Ngày tải lên: 18/02/2014, 04:20

... Statistical Methods for Survival Data Analysis Statistical Methods for Survival Data Analysis Third Edition ELISA T LEE JOHN WENYU WANG Department of Biostatistics and Epidemiology and Center for American ... electronic formats Some content that appears in print, however, may not be available in electronic format Library of Congress Cataloging-in-Publication Data: Lee, Elisa T Statistical methods for survival ... sciences The third edition of Statistical Methods for Survival Data Analysis is intended to provide a comprehensive introduction of the most commonly used methods for analyzing survival data It begins...

Ngày tải lên: 29/06/2014, 10:20

... described in this study A need for such procedures derives from the prospect of developing a prediction model for violent crime rates which is of immediate interest for public services such as social ... both methods by analyzing nycthemeral rhythms of offenses against the person causing bodily harm and in the conclusion limitations, modifications and alternatives to our methods are discussed Methods ... test for finding the frequencies of oscillating data is described Using harmonic frequencies the data are modeled as a sum of sine and cosine oscillations and a Fourier transform is performed...

Ngày tải lên: 10/08/2014, 09:20

... STATISTICAL METHODS FOR ENVIRONMENTAL SCIENCE In situations where a two-way categorization of the data exists, the expected values may be estimated from the marginals For example, the formula for chi-square ... developed for estimating the expected extreme values for several distributions which are unlimited in the range of values which can be taken on by their extremes Some information is also available for ... another condition, or main effect, there is a term RCij which is associated with that particular combination of levels of the main effects Such effects are known as interaction effects Basic assumptions...

Ngày tải lên: 10/08/2014, 20:20

... Statistical Methods for Survival Data Analysis Statistical Methods for Survival Data Analysis Third Edition ELISA T LEE JOHN WENYU WANG Department of Biostatistics and Epidemiology and Center for American ... electronic formats Some content that appears in print, however, may not be available in electronic format Library of Congress Cataloging-in-Publication Data: Lee, Elisa T Statistical methods for survival ... sciences The third edition of Statistical Methods for Survival Data Analysis is intended to provide a comprehensive introduction of the most commonly used methods for analyzing survival data It begins...

Ngày tải lên: 14/08/2014, 05:20

... Nonparametric Methods of Estimating Survival Functions In this chapter we discuss methods of estimating the three survival (survivorship, density, and hazard) functions for censored data Unfortunately, ... are known Therefore, we suggest using nonparametric methods to analyze survival data before attempting to fit a theoretical distribution If the main objective is to find a model for the data, estimates ... are, respectively, a complete decennial life table for the total U.S population for 1989—1991 and an abridged life table for the same population for 1998 The abridged table in Table 4.5 was constructed...

Ngày tải lên: 14/08/2014, 05:20

... >) is equal to e(t ) for t - t> Thus w for censored G G H H G observations t> equals 9e(t ), where t - t> For example, w for 16> is G G H H G 9e(15), or 90.100, and that for 18> is 9e(18), or ... (1964) suggests using the scores t , , t as before for the failures and L NL t for all censored observations The mean score, for example, for the N> L first group is r t  ; (n r )t   ... CHD after adjusting for the effects of smoking Example 5.8 Table 5.7 gives survival data in life-table format of male cases with localized cancer of the rectum in Connecticut for 1935—1944 and...

Ngày tải lên: 14/08/2014, 05:20

... and  for samples with and without censored observations 7.4.1 Estimation of and for Data without Censored Observations Estimations of and  for complete samples by maximum likelihood methods ... t ) : 15.43 Therefore R : 0.84 and G G G G 1/(1 R) : 6.25 From Table B-10,  : 2.89830 for 1/(1 R) : 6.0 and  : 3.14984 for 1/(1 R) : 6.5 By linear interpolation, for 1/(1 R) : 6.25, ... p and solving for t , that is, N N t : 9log p/  For example, the median (50th percentile) survival time can be N estimated by t : 9log 0.5/  : 6.539 weeks   Estimation of for Data with Censored...

Ngày tải lên: 14/08/2014, 05:20

... * * @A : 9log for the exponential and the extended generalized gamma, :9(1/ ) log for the Weibull, : for the lognormal, and :9(1/ ) log for the log-logistic distribution A B : 1/ for the Weibull ... to provide a value for SHAPE1 BMDP does not have a procedure for the gamma distribution For the Weibull, lognormal, and log-logistic distributions, we need to provide values for CONSTANT and SCALE ... diets in Table 3.4 We select the lognormal distribution for this —   217 set of data for illustrative purposes Using methods discussed in Chapter 7, the MLE of the parameters...

Ngày tải lên: 14/08/2014, 05:20

... either for the dependent variable or for the independent variables, is missing This problem is obviously less critical if 1% of data for one independent variable is missing than if 40% of data for ... of surviving a given time  G for rats fed with any of the diets For example, for rats fed a low-fat diet,    273 Table 11.3 Analysis Results for Rat Data in Table 3.4 Using ... value for cell type A and otherwise, and x , taking the value for cell  type B and otherwise Clearly, if there are only two categories (e.g., sex), only one dummy variable is needed: x is for...

Ngày tải lên: 14/08/2014, 05:20

... function for the other strata and for the entire data set in Table 13.6 can be constructed in a similar manner If we ignore the stratum-specific effect and are interested only in the average overall effect ... for all the other variables For example, in Example 14.4, the regression coefficient for the gender variable, 90.279, is an estimate of the log odds ratio for females versus males, adjusting for ... class (or group) For example, for the 990% class, the odds ratio is 13;12/4;3 : 13 The 95% confidence intervals for the ORs are obtained using (14.1.6) Although the odds ratio for the 46—90% group...

Ngày tải lên: 14/08/2014, 05:21

... higher) for a 1-unit increase in LINSUL from the model for IFG versus NFG SBP is not significant in the model for IFG versus NFG (p : 0.2346) Neither SBP nor LINSUL is significant in the model for ... 9, 11, and 12 to perform additional statistical inferences For instance, we can test whether the coefficients for SBP in the first two models are equal (whether the odds ratio for a 1-unit increase ... [exp(0.026)] times (or 3% higher) for a 1-unit increase in SBP, and 2.85 [exp(1.047)] times (or 185% higher) for a 1-unit increase in LINSUL from the model for DM vs NFG The odds ratio is 2.40...

Ngày tải lên: 14/08/2014, 05:21

... Blackwell Scientific, Oxford Hill, A B (1960b) Statistical Methods in Clinical and Preventive Medicine Oxford University Press, Oxford Hill, A B (1971) Principles of Medical Statistics Oxford University ... the Effects of Patient Case Mix on Length of Hospital Stay: A Proportional Hazards Frailty Model Approach Methods of Information in Medicine, 40(4), 288—292 Lee, E T (1980) Statistical Methods for ... (1987) Statistical Methods for Psychology Duxbury Press, Boston Hung, C T., Lim, J K C., and Zoest, A R (1988) Optimization of High-Performance Liquid Chromatographic Analysis for Isoxazolye Penicillins...

Ngày tải lên: 14/08/2014, 05:21

... Statistical Methods for Survival Data Analysis Statistical Methods for Survival Data Analysis Third Edition ELISA T LEE JOHN WENYU WANG Department of Biostatistics and Epidemiology and Center for American ... electronic formats Some content that appears in print, however, may not be available in electronic format Library of Congress Cataloging-in-Publication Data: Lee, Elisa T Statistical methods for survival ... sciences The third edition of Statistical Methods for Survival Data Analysis is intended to provide a comprehensive introduction of the most commonly used methods for analyzing survival data It begins...

Ngày tải lên: 14/08/2014, 09:22

... Nonparametric Methods of Estimating Survival Functions In this chapter we discuss methods of estimating the three survival (survivorship, density, and hazard) functions for censored data Unfortunately, ... are known Therefore, we suggest using nonparametric methods to analyze survival data before attempting to fit a theoretical distribution If the main objective is to find a model for the data, estimates ... are, respectively, a complete decennial life table for the total U.S population for 1989—1991 and an abridged life table for the same population for 1998 The abridged table in Table 4.5 was constructed...

Ngày tải lên: 14/08/2014, 09:22

... >) is equal to e(t ) for t - t> Thus w for censored G G H H G observations t> equals 9e(t ), where t - t> For example, w for 16> is G G H H G 9e(15), or 90.100, and that for 18> is 9e(18), or ... (1964) suggests using the scores t , , t as before for the failures and L NL t for all censored observations The mean score, for example, for the N> L first group is r t  ; (n r )t   ... CHD after adjusting for the effects of smoking Example 5.8 Table 5.7 gives survival data in life-table format of male cases with localized cancer of the rectum in Connecticut for 1935—1944 and...

Ngày tải lên: 14/08/2014, 09:22

... and  for samples with and without censored observations 7.4.1 Estimation of and for Data without Censored Observations Estimations of and  for complete samples by maximum likelihood methods ... t ) : 15.43 Therefore R : 0.84 and G G G G 1/(1 R) : 6.25 From Table B-10,  : 2.89830 for 1/(1 R) : 6.0 and  : 3.14984 for 1/(1 R) : 6.5 By linear interpolation, for 1/(1 R) : 6.25, ... p and solving for t , that is, N N t : 9log p/  For example, the median (50th percentile) survival time can be N estimated by t : 9log 0.5/  : 6.539 weeks   Estimation of for Data with Censored...

Ngày tải lên: 14/08/2014, 09:22

... * * @A : 9log for the exponential and the extended generalized gamma, :9(1/ ) log for the Weibull, : for the lognormal, and :9(1/ ) log for the log-logistic distribution A B : 1/ for the Weibull ... to provide a value for SHAPE1 BMDP does not have a procedure for the gamma distribution For the Weibull, lognormal, and log-logistic distributions, we need to provide values for CONSTANT and SCALE ... line with unit slope and zero intercept Therefore, a Figure 8.13 Cox—Snell residual plot for the fitted lognormal model on the tumor-free time data for rats fed with saturated diets ...

Ngày tải lên: 14/08/2014, 09:22