The Error in X, Y or Z component of shrinkage result indicate the percentage of shrinkage that occurs in the part in the direction of the X, Y and Z axes, respectively, as a difference from the average shrinkage in that direction.
A part which is oriented perpendicular to an axis will show negative error in shrinkage in that axis' direction.
Use this result to see which parts of your model shrink more or less than average. Results closer to zero indicate places where the model has shrunk evenly and will therefore maintain its shape.
Look for regions where high differential shrinkage exist. These regions are more likely to deform.