Modeling and Multivariate Methods - SAS

Chapter 3 Fitting Standard Least Squares Models 59
Regression Reports
Table 3.3 Description of the Summary of Fit Report (Continued)
Mean of Response
Observations (or Sum
Wgts)
AICc
BIC
Overall mean of the response values.
Records the number of observations used in the model. If there are no
missing values and no excluded rows, this is the same as the number of rows
in the data table. If there is a column assigned to the role of weight, this is
the sum of the weight column values.
Note: Appears only if you have the AICc option selected.
Shows or hides the corrected Akaike Information Criterion value, which is a
measure of model fit that is helpful when comparing different models.
Note: Appears only if you have the AICc option selected.
Shows or hides the Bayesian Information Criterion value, which is a measure
of model fit that is helpful when comparing different models.
Analysis of Variance
The Analysis of Variance report provides the calculations for comparing the fitted model to a simple mean
model.
Table 3.4 Description of the Analysis of Variance Report
Source
DF
Sum of Squares
Lists the three sources of variation: Model, Error, and C. Total (Corrected
Total).
Records an associated degrees of freedom (DF) for each source of variation.
• The C. Total DF is always one less than the number of observations.
• The total DF are partitioned into the Model and Error terms:
– The Model degrees of freedom is the number of parameters (except
for the intercept) used to fit the model.
– The Error DF is the difference between the C. Total DF and the
Model DF.
Records an associated sum of squares (SS) for each source of variation. The
SS column accounts for the variability measured in the response.
• The total (C. Total) SS is the sum of squared distances of each response
from the sample mean.
• The Error SS is the sum of squared differences between the fitted values
and the actual values. This corresponds to the unexplained variability
after fitting the model.
• The Model SS is the difference between the C. Total SS and the Error
SS.