MAST works by dimensionalizing (or slicing and dicing) volumes. A ‘dimension’ is something like gender, occupation, or state of residence – a way to categorize things, but it doesn’t make sense to add it up like dollars. Dollars, people, and households are examples of volumes – things that can be added up sensibly.
There are many data items in the census, like FULP, ELEP, PINCP, HINCP, etc. where the census bureau combined both volumetric and dimensional data in a single data item. E.g. a ‘2’ might mean that the household didn’t use the item (dimensional), but a ‘4’ means that they spent $4 on it (volumetric). In order for MAST to work powerfully, I had to break these data items into two, e.g. FULP_V and FULP_D, respectively containing the volumetric and dimensional portions of the data.
But if you’re going to accumulate the volumetric portion, you will need it to be weighted. So FULP_VW was born, to contain the volumetric weighted portion. And since it is a multiyear file, you will often want it adjusted, so FULP_VA came into existence. And sometimes you will want it weighted and adjusted, which gives us FULP_VWA.