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About AnalystSoft

Purpose

This procedure performs regression with linear and polynomial (second or higher order) terms of a single predictor variable and plots a regression curve through the data. Polynomial regression is one method for modeling curvature in the relationship between a response variable (Y) and a predictor variable (X) by extending the simple linear regression model to include higher order terms (X2,X3,...) as predictors.

Preparations   

    Run Statistics→Regression→Polynomial regression...

Results

R2 (R-Square) Coefficient of determination; indicates how much variation in the response is explained by the model. The higher the R2 , the better the model fits your data.
Adjusted R-Square Accounts for the number of predictors in your model and is useful for comparing models with different numbers of predictors. The formula is:
1 -         MS Error       
SS Total / DF Total
Sum of squares (SS) The sum of squared distances. SS Total is the total variation in the data. SS Regression is the portion of the variation explained by the model, while SS Error is the portion not explained by the model and is attributed to error.
Degrees of freedom (d.f.) Indicates the number of independent pieces of information involving the response data needed to calculate the sum of squares. The degrees of freedom for each component of the model are:
DF Regression = p
DF Error = n - p - 1
Total = n - 1
where n = number of observations and p = number of predictors.
MS Regression Mean square regression. The formula is:
SS Regression
DF Regression
MS Error Mean square error, which is the variance around the fitted regression line. MS Error = s2. The formula is:
SS Error
DF Error
F If the calculated F-value is greater than the F-value from the F-distribution, then at least one of the coefficients is not equal to zero. The F-value is used to determine the p-value. The formula for the calculated F-value is:
MS Regression
MS Error
Residuals The difference between the observed values and predicted values.