The Importance of Unit of Analysis in Defining Context

The animated map to the right reveals the importance of scale or unit of analysis in defining context.  This example shows the spatial variation in the same variable (per capita income), but at three different geographical units (blockgroup, tract and zipcode).  The former are conventional census geographies and the latter is an alternative geography, but one increasingly encountered in applied demography.

As researchers begin to think about the possibilities for adding in contextual level data to their previously gathered data on individuals (or other units of analysis - e.g., firms, clinics, etc.), it is important to give careful consideration to issues associated with defining the appropriate context. With GIS we can easily link an individual address to attributes of a larger geographical unit, and typically many sociologists and demographers choose to define neighborhood based on census tracts.  However, is the "census tract" the appropriate context?  The answer inevitably depends upon the nature of the study and the dependent variables and outcome measures one is using.

Last modified: 03/01/06 | Contact Webmaster