entire sample. The MIPS detected sources all belong to the most massive end of the stellar mass distribution, while other properties such as age and morphology (see later) are in the average range. In particular the mean log(Mass) of MIPS detected galaxies is 0.48 dex higher than the rest of the sample, and this can explain the higher detection rate for .\
Reddy et al. (2006) found similar results for optically selected ($UGR$) star-forming galaxies at z$\sim$ 2: the age distributions of 24$\mu m $ detected and non-detected galaxies are similar, while the mass distributions are offset such that undetected galaxies have an average $log(M)$ of 0.4 dex lower than for 24$\mu$ detected galaxies. The MIPS detected galaxies have weaker  emission and stronger interstellar absorption lines, consistent with our results.\
Following the approach outlined in Santini et al. we derived the total IR luminosity and then the MIPS-Inferred total SFR. As noted by Reddy et al. 2006, the conversion from the 24$\mu m$ flux to total IR luminosity and then to unobscured SFR are subject to many uncertainties. For our galaxies, accurate spectroscopic redshifts are known and this gives the advantage of knowing precisely the location of the PAH features 