Table 1.
Tree analysis of covariate effects for the WJ-II Calculation outcome. For each cluster, the cluster rules and the number(proportion) of observations are given with the mean (SD) for the pre- and post-natal MeHg exposure (in ppm). The means (SD) in each cluster for all 7 outcomes are included in this Table which are the estimated cluster means αi’s in Model 1.
| Cluster 1 | Cluster 2 | Cluster 3 | Cluster 4 | |
|---|---|---|---|---|
| Cluster rules | SES<26.25 | SES>=26.25 | ||
| K-BIT<67.5 | K-BIT>=67.5 | |||
| recent postnatal MeHg <=13.10ppm | recent postnatal MeHg >13.10ppm | |||
| Number (proportion) of observations | 65 (14.32%) | 178 (39.21%) | 26 (5.73%) | 185 (40.75%) |
| Prenatal MeHg (ppm) | 6.33 (4.21) | 7.27 (4.35) | 7.87 (5.10) | 6.71 (4.41) |
| Recent postnatal MeHg (ppm) | 8.54 (4.79) | 7.16 (3.13) | 17.16 (3.79) | 7.43 (4.56) |
| mean (estimated cluster mean αi in Model 1) and (SD) | ||||
| WJ-II Calculation | 75.20 (19.31) | 84.97 (14.47) | 73.54 (14.70) | 90.42 (15.35) |
| WJ-II Applied Problems | 77.69 (15.19) | 85.58 (13.16) | 77.23 (11.58) | 91.26 (13.29) |
| CVLT Long Delay (scaled) | −1.23 (1.32) | −0.71 (1.26) | −1.44 (1.02) | −0.49 (1.20) |
| CVLT Short Delay (scaled) | −1.26 (1.34) | −0.57 (1.20) | −1.37 (1.20) | −0.42 (1.18) |
| CANTAB IED Log Total Trials | 4.84 (0.34) | 4.73 (0.33) | 4.82 (0.29) | 4.69 (0.35) |
| CANTAB IED Log pre-ED Errors | 2.25 (0.50) | 2.20 (0.48) | 2.33 (0.64) | 2.06 (0.47) |
| CANTAB SRM Sqrt Between Errors | 5.42 (1.73) | 5.05 (1.65) | 4.95 (2.29) | 4.53 (1.69) |
SES= Hollingshead socioeconomic status, K-BIT=Matenral IQ, IED = Intra-Extra Dimensional Shift Set, SRM = Spatial Recognition Memory.