Parameter Estimation and Evaluation Population and Distribution Model Population and Distribution Model The hazard rate may not be the same for all individuals. To control heterogeneity across individuals,we assume that the individual-specific hazard rate depends on some individ- ual characteristics Xi (e.g.,age,gender,race,education,work experience)via the form Strata→Sex=1+Sex=2 1.00 Xi(t)ex:0Xo(t), 0.75 whereλo(t)is called a baseline hazard function. 0e9o, This model,proposed by Cox (1972),is called a proportional hazard 0.25 model. 0.00 0 250 500 750 1000 Time Parameter Estimation and Evaluation Introduction to Statistics and Econometrics April 21,2020 12/207Parameter Estimation and Evaluation Parameter Estimation and Evaluation Introduction to Statistics and Econometrics April 21, 2020 12/207 Population and Distribution Model Population and Distribution Model