The instinct is reasonable: if assortment varies by pincode, cover every pincode. In practice that is expensive and
frequently no more informative.
What actually varies
Pincodes within the same catchment type tend to behave similarly. Two dense-metro pincodes three kilometres apart
usually carry comparable assortment at comparable prices. The variation that matters is between catchment
types — dense metro against suburban edge, affluent residential against mixed.
A stratified panel covering each catchment type with several points captures that variation. An exhaustive sweep
captures it too, plus a great deal of redundancy, at several times the cost.
The arithmetic
Cost scales with pincodes × SKUs × observations per day. A metro with 300 pincodes, 2,000 SKUs
and two daily observations is 1.2 million observations per day before you add a second platform. A 42-pincode panel on
the same SKUs is a seventh of that.
What we owe you in exchange
A written statement of what the panel represents and what it does not. Our proposals carry
represents and does_not_represent as explicit fields, because a sample is only defensible
if its limits are stated.
If your analysis genuinely needs every pincode — a coverage-obligation question, say, rather than a pricing
one — we will build it. We would just rather you chose that deliberately than by default.