Re: Effect of FOCE vs FOCE INTER on success of covariance step within a model with additive error

From: Takuya Okagaki okagaki@tanabe.co.jp Subject: Re: [NMusers] Effect of FOCE vs FOCE INTER on success of covariance step within a model with additive error Date: Fri, 10 Mar 2006 15:29:49 +0900 Dear Sameer When we simulated the datasets which followed a normal distribution, the estimates which resulted from good convergence using FOCE corresponds with those using FOCE INTER. (Dr Beal told us that the estimates using FOCE and FOCE INTER should be equal if the data followed a normal distribuion.) However, some datasets showed not convergence using both methods, some other datasets showed not convergence using FOCE but FOCE INTER, and conversely, some other datasets showed not convergence using FOCE INTER but FOCE. When many outlying values existed (but they follow a normal distribution strictly), the FOCE and FOCE INTER methods cound not converge. For datasets on a thin line between convergence or not convergence, results to converge using FOCE might not be consist with those using FOCE INTER. INTER option requires many calculations for matrix, so there might be a delicate difference of a convergent result between FOCE INTER and FOCE methods. Takuya Okagaki Statistical Analysis Section Clinical Research Planning & Coordination Department Clinical Research Division Tanabe Seiyaku Co., Ltd. e-mail: okagaki@tanabe.co.jp tel: +81-6-6205-5835 fax: +81-6-6205-5223