Page 20 - Regression Guideline

Savvi"Sample"Report"
Savvi
Statistical Analysis Value Verification Indicator
Multivariate Analysis
Number of variables 14
Sample size 386
Records for analysis 386
Multivariate Regression
In the next and final step, only those property characteristics significant in the previous bivariate models are retained and entered into a single multivariate regression model. This model examines the associations among the remaining variables to further weed out those that overlap with other variables in terms of predicting price. A technique called stepwise regression is used to examine each variable against all other possible variables. Only those variables that uniquely continue to account for a significant percentage of the price variation in the properties examined remain in the final model as a predictor set. The effects of the variables removed from the model are subsumed within and accounted for by the remaining variables. #
The overall model (all remaining property characteristics as a set) is tested for statistical significance using an F-test, which compares the amount of price variation explained by the model to the variation that is not explained. Significance means the model reliably estimates price variation in the examined properties at the 95% confidence level. The interpretation of the coefficients, % price variation, and statistical significance is the same as in the bivariate models.
Variable
Main Square Feet Basement Square Feet Garage Spaces Bathrooms
Acres Style
Coefficient
109.8972 51.5470 24576.4968 24358.5444 240865.2904 46917.0871
R-Square: 0.60091
F-Statistic: 81.309
The variables below are not statistically significant and do not uniquely account for price variation. They are excluded from the final model. Their effect on price is accounted for by the smaller set of variables above that remain statistically significant. This makes the final model more efficient and equally accurate as if these variables had been included; in effect, they are included.
Style(SL)
Year of construction
Basement Finished Square Feet Bedrooms
Bank owned
Pool
Style(2S)
Walkout Basement(ZERO) Walkout Basement(ONE) Walkout Basement(UNKNOWN) Style(UNKNOWN)
4 19"