Cuối cùng, ứng dụng của chúng ta về cách tiếp cận cấu trúc hiệp phương sai các dữ liệu BHPS cho thấy bằng chứng về sự thiên vị trong việc lập dự toán của các thành phần không đúng khi sử dụng GLS với một ma trận hiệp phương sai V ước tính từ dữ liệu. | CONCLUDING REMARKS 219 Finally our application of the covariance structure approach to the BHPS data showed evidence of bias in the estimation of the variance components when using GLS with a covariance matrix V estimated from the data. This accords with the findings of Altonji and Segal 1996 . This evidence suggests that it is safer to specify V as the identity matrix and use Rao Scott adjustments for testing. Analysis of Survey Data. Edited by R. L. Chambers and C. J. Skinner Copyright 2003 John Wiley Sons Ltd. ISBN 0-471-89987-9 CHAPTER 15 Event History Analysis and Longitudinal Surveys J. F. Lawless . INTRODUCTION Event history analysis as discussed here deals with events that occur over the lifetimes of individuals in some population. For example it can be used to examine educational attainment employment entry into marriage or parenthood and other matters. In epidemiology and public health it can be used to study the relationship between the incidence of diseases and environmental dietary or economic factors. The main objectives of analysis are to model and understand event history processes of individuals. The timing frequency and pattern of events are of interest along with factors associated with them. Time is often the age of an individual or the elapsed time from some event other than birth for example the time since a person married or the time since a disease was diagnosed. Occasionally time may refer to some other scale than calendar time. Two closely related frameworks are used to describe and analyze event histories the multi-state and event occurrence frameworks. In the former a finite set of states 1 2 . K is defined such that at any time an individual occupies a unique state for example employed unemployed or not in the labour force. In the latter the occurrences of specific types of events are emphasized. The two frameworks are equivalent since changes of state can be considered as types of events and vice versa. This allows a unified .
