1. An evaluation method of evaluating optical characteristics of a projection optical system by obtaining, by a prediction formula, a predicted value for a fluctuation amount of the optical characteristics relative to an exposure period of a substrate via the projection optical system, the method comprising: determining the prediction formula by using a dedicated pattern in which a plurality of marks are arranged in a matrix on an object plane of the projection optical system, wherein the determining includes selecting, from the plurality of marks, at least two marks located in an illuminated region to be formed on the object plane when exposing the substrate, and obtaining the prediction formula based on positions of images of the at least two marks formed on an image plane of the projection optical system.