Comparison of same-day measurements of field strengths of 100 sunspots observed at MWO and CrAO. Observations from 1994 to 2003 are shown by black squares, and data for 2004–2014 are shown as filled red circles. The solid line indicates the least-squares fit by the first degree polynomial with errors in both MWO and CrAO data. The coefficients of best-fit line for all data are shown in low-right side of the figure.