针对马尔科夫链蒙特卡洛(MCMC)做参数估计因初值不好而链长太长且耗时太久的缺陷,利用MonteCarlo模拟进行研究,结果发现:使用MCMC进行估计项目反应理论中2PLM的未知能力参数和项目参数,当样本量或项目量较大,且链长较短时,初值作用明显,比较准确的初值估计精度更高.这个发现可以在一定条件下,弥补MCMC耗时太久的缺陷.
To implement a Markov Chain Monte Carlo(MCMC) method,one of important issues is the choice of starting values.If MCMC sampler started at poor initial values,the chain is taking a long time to move around the parameter space,therefore it will take longer to converge to the stationary distribution.To remedy the defect of MCMC,the special initial values of the unknown parameters in the 2-parameter Logistic model are employed to be the initial values of the MCMC.The results of the Monte Carlo simulation show that the scheme could greatly speed up MCMC convergence.