New Methods: Sparsity

• Is it meaningful to use many attributes?

• • Tentatively, yes
  • Not a meaningful 13-way distribution
  • But, a link between many statistically valid low-order distributions (e.g., 3-way)

• If acceptable, can we do better than standard IPF?

• Yes - use a sparse data structure instead of a complete array to represent table

• Store only non-zero cells in table