Comparison of the model with different data sets: a) PMOD composite (1996–2009); b) PMOD composite (1999–2009); c) TIM; e) ACRIM II, and of the PMOD composite with the measurements by the two other individual instruments: d) TIM and f) ACRIM II. The coloured straight lines show the slopes of the linear regressions between the compared sets. The dashed black line shows the expected ideal slope of 1. In each panel, the corresponding correlation coefficient, R_c, and the slope are indicated.