Critical case sampling

crucial case

A critical case is one that permits analytic generalisation, as, if a theory can work in the conditions of the critical case, it's likely to be able to work anywhere.

Characteristics of particular cases may make them critical – level of education of the population, level of pollution of the environment, level of resistance to government intervention of a community. The purpose of the evaluation is to investigate the success of the program in this particular critical case. Commissioners of the evaluation may be interested in the results of the evaluation for logical generalisation to other sites.

Polar regions and small island states are identified by scientists as critical cases in investigating the phenomenon of climate change. These sites are monitored closely for environmental changes. By investigating these sites in depth, scientists hope to develop knowledge that can be applied to other sites.


Suppose national policymakers want to get local communities involved in making decisions about how their local program will be run, but they aren't sure that the communities will understand the complex regulations governing their involvement. The first critical case is to evaluate the regulations in a community of well-educated citizens. If they can't understand the regulations, then less-educated folks are sure to find the regulations incomprehensible. Or, conversely, one might consider the critical case to be a community consisting of people with quite low levels of education: 'If they can understand the regulations, anyone can.' (Patton 2014: 276)



Patton, M. Q. (2014). Qualitative Research & Evaluation Methods: Integrative Theory and Practice​. SAGE Publications.

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'Critical case sampling' is referenced in:

  • Framework/Guide

    • Rainbow Framework :