Frailty, Advanced Statistics

Assignment Help:

A term usually used for unobserved individual heterogeneity. Such variation is of main concern in the medical statistics particularly in the analysis of the survival times where hazard functions can be strongly influenced by the selection effects operating in the population. There are several possible sources of this heterogeneity, the most apparent of which is that it reflects the biological differences, so that, for instance, some individuals are born with the weaker heart, or a genetic disposition for cancer. A further prospect is that the heterogeneity happens from the occured weaknesses which result from the stresses of life. Failure to take account of this kind of variation might often obscure comparisons between groups, for instance, by measures of relative risk. A simple model which attempts to permit for the variation between individuals is given as follows


1270_fraility.png 


where Z is the quantity specific to an individual, considered as the random variable over the population of individuals, and the base rate is denoted by λ(t) . What is observed in a population for which this type of model holds is not the individual hazard rate but the net result for several individuals with different values of Z.

 


Related Discussions:- Frailty

Distance sampling, The technique of sampling used in the ecology for determ...

The technique of sampling used in the ecology for determining how much plants or animals are in a given fixed region. A set of randomly placed lines or points is recognized and the

Barnard, Barnard, George Alfred (1915^2002) : Born in Walthamstow in the ea...

Barnard, George Alfred (1915^2002) : Born in Walthamstow in the east of London, Barnard achieved a scholarship to St. John's College, Cambridge, from where he graduated in the math

Case-control study, Case-control study : The traditional case-control study...

Case-control study : The traditional case-control study is the common research design in the epidemiology where the exposures to risk factors for cases (individuals getting the dis

Function of Power, In an experiment, power is a function of 1. The number o...

In an experiment, power is a function of 1. The number of variables being measured and the beta level 2. The effect size, internal validity and the beta level 3. The number of part

1, In a mathematics examination the average grade was 82 and the standard d...

In a mathematics examination the average grade was 82 and the standard deviation was 5. all students with grade from 88 to 94 received grade of B. if the grade are approximately no

Pasture trials, Pasture trials is the study in which the pastures are subj...

Pasture trials is the study in which the pastures are subjected to number of treatments (types of forage, animal management systems, agronomic treatments, and many more)The grazin

Percentage, Looking for the correct answer.Y=50+.079(149)-.261(214)=

Looking for the correct answer.Y=50+.079(149)-.261(214)=

Define interval-censored observations, Interval-censored observations ar...

Interval-censored observations are the  observations which often occur in the context of studies of time elapsed to the particular event when subjects are not monitored regularl

Bivariate survival data, Bivariate survival data : The data in which the tw...

Bivariate survival data : The data in which the two related survival times are of interest. For instance, in familial studies of disease incidence, data might be available on the a

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd