Mezue ahịrịokwu na-esonụ: Kaadị nkesa ntụpọ na-etinye obere akara ntụpọ n'elu ohere enyere iji gosipụta nkesa nke ihe omume enyere. Ọnọdụ nke ntụpọ ọ bụla nwere ike na-anọchi anya ọnọdụ nke otu ihe atụ, dị ka na map nke Dr. Snow mere n'oge
1854 Ọrịa ọgbụgba na Broad Street, ebe ntụpọ ọ bụla na-anọchi anya otu ọnwụ n'ihi ọgbụgba. N'aka nke ọzọ, enwere ike ịdepụta data nchịkọta ọnụ ọgụgụ (otu a na-eji na map choropleth) site n'itinye ntụpọ na mpaghara nchịkọta ọ bụla (dịka, mba, steeti, obodo) iji gosipụta njupụta nke ihe atụ; a na-akpọkarị ụdị nke ikpeazụ a "kaadị njupụta ntụpọ".