What is the difference between rectangular and hierarchical data?
The MPC microdata projects deliver rectangular data by default. The rectangularized data file does not retain households as separate records. Household information is put on the person records of each individual in the household. With rectangularization, there are no separate household records in the data extract. No information is lost, and most researchers prefer this format.
The rectangular format default can, however, be overridden in most projects and samples to yield hierarchical data consisting of household records followed by the person records of household members.