the best quadratic unbiased estimation (bque) of variance components in the gauss-helmert model is used to combine adjustment of gps/levelling and geoid to determine the individual variance components for each of the three height types. through the research, different reasons for achievement of the negative variance components were discussed and a new modified version of the best quadratic unbi...

This study demonstrated the equivalence between the Rasch testlet model and the three-level one-parameter testlet model and explored the Markov Chain Monte Carlo (MCMC) method for model parameter estimation in WINBUGS. The estimation accuracy from the MCMC method was compared with those from the marginalized maximum likelihood estimation (MMLE) with the expectation-maximization algorithm in Con...