Relation between log﹩{R}_{{\rm{IRT}},{\rm{cat}}}^{{\prime} }﹩ and stellar age for OC members (blue dots) and WD-MS binaries (red dots). Diamonds represent the median log﹩{R}_{{\rm{IRT}},{\rm{cat}}}^{{\prime} }﹩ within each age bin. The uncertainties are calculated using the 16th and 84th percentiles. Gray dashed lines are the dividing lines for each time bin.