Nearly all castable materials show some shrinkage.  A quick qualitative test can be done by casting a sample in a curry tub.  After setting the shrinkage is visible on the surface of the curry tub.  If the castable is still in contact with the curry tub this is clearly visible from the outside.  This means that there is 0% shrinkage or there is a slight expansion.  If it is difficult to stop from the curry tub, there is an expansion.  If it is very difficult to strip then there is a large expansion.  In this case you can usually see a distortion in the bottom of the curry tub.  With high shrinkage usually only the bottom middle of the curry tub is seen to still be in contact.  This surface is normally glossy.  By pressing the sides of the curry tub inwards you can get some idea of the extent of the shrinkage.  If there is 0% shrinkage then the whole surface of the curry tub is glossy.