1. A method for detecting hot spots from overlay error data for at least one photolithography defined device, the overlay error data corresponding to data for a plurality of sites on a substrate for the at least one photolithography defined device, the method comprising: converting the overlay error data to residual overlay data indicating a residual overlay error for each of the plurality of sites, the residual overlay error being based on an expected overlay error for each of the plurality of sites; determining whether at least one group of overlay error sites is present in the residual overlay data, each of the at least one group including at least two nearest neighbor sites of the plurality of sites, each of the at least two nearest neighbor sites having the residual overlay error greater than a threshold; for each of the at least one group of overlay error sites present, determining whether each of the at least one group of overlay error sites fits a physical model for a hotspot, each of the at least one group of overlay error sites fitting the physical model being categorized as a hotspot; and determining a plurality of parameters for the hotspot for each of the at least one group of overlay error sites that fits the physical model, wherein the step of determining whether each of the at least one group of overlay error sites fits a physical model for a hotspot further includes: determining a shape of a polygon for each of the at least one group of overlay error sites; determining whether the shape has a circularness exceeding a shape threshold; and retaining at least a portion of the plurality of the groups of overlay error sites having the circulamess exceeding the threshold to provide at least one hot spot candidate.