Correlation coefficient matrix of our cross-correlation measurements. The colour scale is from 0 (black) to 1 (white). Each block enclosed by a white grid is the covariance between each pair of cross-correlations indicated with ticks (bin p × ν GHz), while that enclosed by a golden grid corresponds to the covariance between the CIB cross-galaxies from each pair of tomographic bins. The matrix has non-zero elements at all cells, but the off-diagonal elements in each cross-correlation are vanishingly small.