Illinois 1959 county gross farm product value per acre

Description

Classic data set for the choice of class intervals for choropleth maps.

Usage

data(jenks71)

Format

A data frame with 102 observations on the following 2 variables.

jenks71

a numeric vector: Per acre value of gross farm products in dollars by county for Illinois in 1959

area

a numeric vector: county area in square miles

Source

Jenks, G. F., Caspall, F. C., 1971. "Error on choroplethic maps: definition, measurement, reduction". Annals, Association of American Geographers, 61 (2), 217–244

Examples

data(jenks71)
(jenks71)