1. An apparatus comprising: a controller including a memory storing instructions and a processor which executes the instructions, the controller being configured to function as: an obtaining unit configured to obtain first image data obtained by reading, performed by a reading unit, a chart on which an image has not been printed by an image forming unit and second image data obtained by reading, performed by the reading unit, a chart on which an image has been printed by the image forming unit; a determination unit configured to determine whether an abnormality has occurred in the reading unit using a feature amount obtained from a result of analyzing the first image data; a correcting unit configured to correct, if the determination unit determines that an abnormality has occurred in the reading unit, a feature amount obtained from a result of analyzing the second image data using the feature amount obtained from a result of analyzing the first image data; and an estimation unit configured to estimate a cause of an abnormality that has occurred in the image forming unit using the feature amount corrected by the correcting unit, wherein, if the determination unit determines that an abnormality has not occurred in the reading unit, the estimation unit estimates a cause of an abnormality that has occurred in the image forming unit using the feature amount obtained from a result of analyzing the second image data.