1. A method of extracting data from an overlay target, the method comprising: (a) providing image information or one or more intensity signals of the overlay target; (b) obtaining an overlay error from the overlay target by analyzing the image information or the intensity signal(s) of the overlay target; (c) obtaining a systematic error metric from the overlay target by analyzing the image information or the intensity signal(s) of the overlay target; and (d) obtaining a noise metric from the overlay target by applying a statistical model to the image information or the intensity signal(s) of the overlay target.