Investigation of splitting test accuracy over different surface stress fields yields Figure \ref{710424} when comparing how well one splitting test result predicts the perpendicular result on the same sample. In contrast Figure \ref{752700} shows how well the test predicts the true input surface stress mean. The contour lines on Figures (\ref{353734} to \ref{890019}) are spaced \(0.1\) apart where the color gradient represents a correlation (Sub-figure A) and \(250\ \mu\epsilon\) where the color gradient represents a standard deviation (Sub-figure B).