如果把survival model引入进来做用户流失,可以解决两方面的问题,第一,可以研究duration,第二,对风险因子具有强解释性。 生存分析实际可以划分为两大块,生存曲线的拟合和风险因子的建模。第一块非常简单,利用Kaplan-Meier (KM) estimate对曲线进行估计即可;第二块本身也不难,但如果引入了时变效果,数据操作难度就相应增...
These models, using the MSIS-86 neutral atmosphere model, include solar EUV photoionization, chemical and collisional processes between the various charged and neutral species. Steady-state results for both near-summer and winter conditions as well as for diurnal evolution are presented and compared ...
A time-dependent model was developed and solved numerically to study a purely buoyant downward flame spread over a thermally thin solid fuel in various gravity environments. According to the specified burn-out solid density and no retained ash, the flame propagation behavior over a thin solid fuel...
This paper focuses on a time-dependent queue model based on the coordinates transformation criterion for operations assessment at a motorway tollgate. This model allows to face the whole spectrum of situations that may characterize a toll booth, some of which often fall outside the boundaries of ...
In this chapter we re-examine Mott's problem introducing a precise definition of the initial state and an explicit formulation of the assumptions on the physical parameters of the model. Then we state the result in a time-dependent setting and we give the details of the proof based on the ...
2) Cox model ###可添加协变量 (with covariates bili, chol and albumin) ROC.bili.cox<-timeROC(T=pbc$time, delta=pbc$status,marker=pbc$bili, other_markers=as.matrix(pbc[,c("chol","albumin")]), cause=1,weighting="cox", times=quantile(pbc$time,probs=seq(0.2,0.8,0.1))) ...
We present some results from the chemical model we have developed to study photon-dominated regions (PDRs), which are surface layers of objects exposed to intense fluxes of far-ultraviolet photons. PDRs are found in very different environments, from giant molecular clouds and planetary nebulae to...
A time-dependent model for the energy of a flaring solar active region is presented based on an existing stochastic jump-transition model (Wheatland and Glukhov in Astrophys. J. 494 , 858, 1998 ; Wheatland in Astrophys. J. 679 , 1621, 2008 and Solar Phys. 255 , 211, 2009 ). The magn...
16 by incorporating oscillatory extinction rates, see “Model”. We then calculate observables such as “Moments” of the particles number, its “Covariance”, “Survival probability”, and the “Avalanche shape” (or temporal profile) and compare them qualitatively to experimental results from Ref...
Zonal Penetration Scale of Model Midlatitude Jets All available observations indicate that the most energetic time-dependent currents are located in the vicinity of intense large-scale oceanic current systems. This characteristic is also a basic property of eddy-resolving gyre-scale num... WR Holland...