TABLE 4.
Simulation study 1: bias and RMSE for unconstrained maximum likelihood (ML) estimation and constrained maximum likelihood (CML) estimation of the latent correlation as a function of the true correlation (ρ), the sample size (N), and different sets of replications.
| Bias |
RMSE |
||||||||||
| Conv+Adm. |
Conv. |
All | Conv+Adm. |
Conv. |
All | ||||||
| ρ | N | ML | CML | ML | CML | CML | ML | CML | ML | CML | CML |
| 0.3 | 30 | 0.022 | 0.055 | 0.043 | 0.068 | –0.016 | 0.352 | 0.358 | 0.395 | 0.395 | 0.411 |
| 50 | 0.025 | 0.035 | 0.040 | 0.049 | –0.003 | 0.284 | 0.288 | 0.310 | 0.309 | 0.328 | |
| 100 | 0.003 | 0.006 | 0.004 | 0.006 | –0.004 | 0.202 | 0.201 | 0.203 | 0.203 | 0.210 | |
| 0.5 | 30 | –0.037 | –0.003 | 0.019 | 0.048 | –0.025 | 0.299 | 0.295 | 0.332 | 0.322 | 0.360 |
| 50 | –0.042 | –0.032 | –0.015 | –0.005 | –0.049 | 0.266 | 0.262 | 0.299 | 0.285 | 0.316 | |
| 100 | 0.000 | 0.002 | 0.006 | 0.008 | 0.003 | 0.196 | 0.194 | 0.202 | 0.201 | 0.206 | |
| 0.7 | 30 | −0.124 | −0.088 | –0.034 | –0.008 | −0.068 | 0.299 | 0.269 | 0.299 | 0.274 | 0.344 |
| 50 | −0.071 | −0.063 | –0.012 | –0.005 | –0.035 | 0.242 | 0.234 | 0.252 | 0.245 | 0.275 | |
| 100 | –0.026 | –0.025 | –0.004 | –0.003 | –0.004 | 0.172 | 0.171 | 0.184 | 0.183 | 0.185 | |
RMSE = root mean square error; ρ = true latent correlation; N = sample size; ML = unconstrained ML estimation; CML = constrained ML estimation. Conv+Adm = all replications in which unconstrained ML converged with admissible values, that is, estimated correlation was within the interval [−1, 1]; Conv = all replications in which unconstrained ML estimation converged and estimated correlations outside [−1, 1] are truncated to −1 or 1; All = all replications (only constrained ML produced estimates for all replications). Biases smaller than −0.05 or larger than.05 are printed in bold.