significant at the .05 level. The dependent variable was the
number of months the patient survived after the diagnosis.
The predictor variables selected for lung cancer were age,
stage, initial treatment, and subsequent treatment. For
breast cancer, they were stage and subsequent treatment.
And, for rectocolon cancer they were sex and stage.
The results show the efficacy of these variables as
predictors of survival. This is demonstrated by a comparison
of these results to the findings of an earlier study (Worden,
Harrison, & Johnston, 1974). A summary of regression data
from the 1974 investigation and from the present study is
given in Table 33.
The regression data from the earlier study (Worden,
Harrison, & Johnston, 1974) are a part of the analysis of
data from six cancer sites that was carried out in the
development of this procedure. For two of the three sites,
the regression equations developed for the present study
represent improvements in the explanation of variability in
survival by the effects of biological, disease, and medical
variables. Also, in the prediction for all three sites the
number of variables included in the regression equations is
considerably reduced. A further demonstration of the
efficiency of these equations for all three cancer sites is
that there is a reduction in the standard error of estimate.