Suchergebnisse

Optimal designs under a survival analysis framework have been rarely considered in the literature. In this paper, an optimal design theory is developed for the typical Cox regression problem. Failure time is modeled according to a probability distribution depending on some explanatory variables through a linear model. At the end of the study, some units will not have failed and thus their time records will be censored. In order to deal with this problem from an experimental design point of view it will be necessary to assume a probability distribution for the time an experimental unit enters the study. Then an optimal conditional design will be computed at the beginning of the study for any possible given time. Thus, every time a new unit enters the study, there is an experimental design to be determined. A particular and simple case is used throughout the paper in order to illustrate the procedure.

The "Acción Transversal del Cáncer", approved on the Spanish Ministry Council on the 11th October 2007; the Instituto de Salud Carlos III-FEDER funds –a way to build Europe- (grants numbers PI08/1770, PI08/0533, PI08/1359, PS09/00773, PS09/01662, PS09/01286, PS09/01903, PS09/02078, PI11/00226, PI11/01403, PI11/01810, PI11/01889, PI11/02213, PI12/00150, PI12/00265, PI12/00488, PI12/00715, PI12/01270, PI14/00613, PI17/00092); the Fundación Marques de Valdecilla (grant number API 10/09); Obra Social CAJASTUR (grant number SV-CAJASTUR-1); Recercaixa (grant number 2010ACUP 00310); Spanish Association Against Cancer (AECC) Scientifc Foundation; Agència de Gestió d'Ajuts Universitaris i de Recerca (AGAUR) –Generalitat de Catalunya (Catalonian Government) (grant numbers 2009SGR1026, 2009SGR1465 and 2017SGR723); and Junta de Castilla y León (grant number LE022A10-2). Sample collection and storage was partially supported by the Instituto de Salud Carlos III-FEDER (grant number RD09/0076/00036), Xarxa de Bancs de Tumors de Catalunya sponsored by Pla Director d'Oncologia de Catalunya (XBTC).