Coefficient of determination, r2
pr2 represents the fraction of the variance in y (vertical scatter from the regression line) that can be explained by changes in x.
pr2, the coefficient of determination, is the square of the correlation coefficient.
Go over point that missing zero is OK - this is messy data, a prediction based on messy data.
Residuals should be scattered randomly around the line, or there is something wrong with your data - not linear, outliers, etc.