Dielectric measurements are advantageous to study materials only when dielectric dispersion is observed in certain frequency and temperature range. This range depends on type of material and also on type of polarisation in the material. If dispersion is observed then one can find out temperature and frequency dependence of dielectric constant and dielectric loss. From the same data one can calculate a.c conductivity also. By analysing the data one can assess the type of polarisation involved. For more details read some standard textbooks on dielectric behaviour of solids and liquids. Many such books can be found on google. You can also go through my research papers available on my Researchgate profile.