The inclusion of covariate which is highly correlated with response can remove a considerable portion of errors, reducing the proportion of errors.
The p values of Tx and age are 0.01 and < 0.001, respectively, which represent a highly significant result. The reason is because age explained a big portion of variability in the response variable (gray colored segment).Īs appeared in Figure 3C, the proportion explained by the ANCOVA model has improved up to 78.8%, mainly due to the contribution of age variable. The proportion of errors has decreased greatly from 0.83 to 0.21 in Figure 3B. One unit increase of age is related to an increase of 0.72 unit in treatment effect.
The size of intercept has reduced greatly by around 31 because it has been adjusted by age. The difference of effect between 2 groups has changed slightly from 11.08 in Equation 4 to 10.18 in Equation 5. Where Tx = 0 for control group and Tx = 1 for experimental group.
0 kommentar(er)
