1. A method for improving a yield of a layout, comprising: selecting a pattern that does not satisfy at least one of a plurality of rules of the layout; adding a margin to a predetermined value of the at least one of the plurality of rules of the selected pattern, based on a ground rule and a recommended rule of each of the plurality of rules; calculating an overall fail rate of the at least one of the plurality of rules that varies according to an addition of the margin; and determining an adjusted margin to be added based on the calculated overall fail rate.