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“Missing strain,” a discrepancy between the total macroscopic strain and the strain contributed by grain boundary sliding (GBS) during superplastic deformation, appears to exist in previous investigations. In this work, the contri¬bution of GBS (ξGBS) and intragranular strain (ξIG) were simultaneously measured using scratch test conducted on AA7475 samples after deformation at 500 °C at initial strain rate of 10-3 s-1. The result shows that the missing strain results most probably from the neglect of the intragranular strain as well as the anisotropic GBS-induced underesti¬mation of ξGBS. The calculation of ξGBS was re-examined, based on the fact that anisotropic shrinkage of samples along width and thickness during superplastic deformation was noted.