  We have performed a multiparametric analysis of luminosity data for a sample
of 234 normal spiral and irregular galaxies observed in X-rays with the {\it
Einstein Observatory}. This sample is representative of S and Irr galaxies,
with a good coverage of morphological types and absolute magnitudes. In
addition to X-ray and optical da ta, we have compiled H-band magnitudes, IRAS
near- and far-infrared, and 6cm radio co ntinuum observations for the sample
from the literature. We have also performed a carefu l compilation of distance
estimates. We have explored the effect of morphology by dividing the sample
into early (S0/a-Sab), intermediate (Sb-Sbc), and late-type (Sc-Irr)
subsamples. The data were analysed with bivariate and multiv ariate survival
analysis techniques that make full use of all the information available in both
detections and limits.
