[en] A quick rough analysis of stellar activity can be accomplished by studying the interrelations of the various observables. Tight correlations between observables suggest general physical relation. The aim of this study is to observe with the IUE satellite a homogeneous sample of stars for which there are extensive coronal data. The X-ray studies of close binaries provided such a sample. Because of intrinsic stellar variability, this type of study is best carried out when all observables are measured simultaneously. So, correlation plots are constructed in which the normalized flux is plotted in a log-log plane against various canonical observables, viz. MgII for the chromosphere, CIV for the transition region, and X-rays for the corona. The author has examined the relations both for the binary sample as a whole, which includes active K and G subgiant RS CVn stars and G main sequence components, and for the K subgiants separately. (Auth.)