WHIP comes from administrative source data. In fact the data on which it is founded is a sample collection extracted from the National Institute of Social Security's (Inps) administrative archives, and have been provided according to an agreement signed between Inps and the University of Torino. The administrative archives from which data have been extracted are:
- unified individual register
- employees’ contributions
- artisans’ contributions
- traders’ contributions
- contributions of the IV gestione separata (atypical workers)
- retirement benefits
- other social security benefits (unemployment subsidies etc.)
- business register
- monthly contributions of firms
The global supply is rather huge – the quantity is around 6 million records provided, for 1.400 million observations (record per variable) – and is growing with new extractions.
Inps provides statistical observatories on most part of these archives, the results of which are published online (see the following page
statistical databases on the Institute website), where it is possible to consult the methodological notes, useful as documentation for WHIP input archives