Table 3 SAS output from linear modelling of BLLs in children by residential distance from smelter and soil lead concentration, year and age.
The REG Procedure Dependent Variable: BLL Blood Lead | ||||||
|---|---|---|---|---|---|---|
Analysis of Variance | ||||||
Source | DF | Sum of squares | Mean square | F value | Pr > F | |
Model | 6 | 20174 | 3362.35333 | 165.59 | <.0001 | |
Error | 2532 | 51414 | 20.30563 | |||
Corrected total | 2538 | 71588 | ||||
Root MSE | 4.50618 | R-Square | 0.2818 | |||
Dependent Mean | 9.75935 | Adj R-Sq | 0.2801 | |||
Coeff Var | 46.17290 | |||||
Parameter Estimates | ||||||
Variable | Label | DF | Parameter estimate | Standard error | t value | Pr > |t| |
Intercept | Intercept | 1 | 15.91313 | 1.24889 | 12.74 | <.0001 |
dist | Distance from smelter (km) | 1 | -3.08310 | 0.29730 | -10.37 | <.0001 |
yr_norm | Normalised year | 1 | -0.57469 | 0.02556 | -22.49 | <.0001 |
age | Age | 1 | 1.01101 | 0.34306 | 2.95 | 0.0032 |
agesq | Age squared | 1 | -0.21409 | 0.05774 | -3.71 | 0.0002 |
agecb | Age cubed | 1 | 0.00910 | 0.00286 | 3.18 | 0.0015 |
soil_pb_ln | Log of residential soil lead (ppm) | 1 | 0.25032 | 0.11501 | 2.18 | 0.0296 |
Parameter Estimates | ||||||
Variable | Label | Standardized estimate | Lower 95% confidence limit | Upper 95% confidence limit | ||
Intercept | Intercept | 0 | 13.46419 | 18.36208 | ||
dist | Distance from smelter (km) | -0.23354 | -3.66607 | -2.50013 | ||
yr_norm | Normalised year | -0.38032 | -0.62480 | -0.52457 | ||
age | Age | 0.60008 | 0.33830 | 1.68372 | ||
agesq | Age squared | -1.74455 | -0.32731 | -0.10088 | ||
agecb | Age cubed | 0.90323 | 0.00349 | 0.01471 | ||
soil_pb_ln | Log of residential soil lead (ppm) | 0.04903 | 0.02481 | 0.47584 | ||