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Florida State University 
Department of Urban and Regional Planning
Planning Methods III: Forecasting 





Topic
Summary
Example
Key Concepts
Lessons to
be Learned
Discussion
Questions
References
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ASSUMPTION TECHNIQUE

Topic Summary

The Assumption Technique is the simplest and most easily performed economic base analysis technique. Recalling that our goal is to allocate all local employment to basic or non-basic sectors, the assumption technique literally "assumes" that certain industries are inherently basic sector jobs and others are non-basic sector jobs.
When utilizing this technique, it is common practice to assume that ALL manufacturing, mining, agriculture, and federal and state governments are basic sector activities because (it is assumed) they rely largely upon non-local conditions. In contrast, all other industries are assumed to be non-basic, or entirely dependent upon local conditions.
From these very rudimentary assumptions, estimates as to the Total Basic and Total Non-Basic Employment for an area can be made. Then, using the formula for the Base Multiplier presented on the Economic Base Page, a multiplier can be calculated for your local area.

Example of Assumption Technique

To see an example of the Assumption technique applied, visit the Assumption Technique Example Page.

Key Concepts

  • The "assumptions" of the Assumption Technique
  • The simplicity of this technique
  • The King County Example
  • Targeting your assumptions to your specific case
  • Possible limitations of this technique (see the discussion questions)

Lessons to be Learned

  • "Although inadequate as a general basic sector estimation procedure, the assumption technique is appropriate for segments of the economy that clearly serve local and non-local markets." (Klosterman, p.128)
  • Often planners must use very basic assumptions in their analytical techniques. These assumptions must be utilized very carefully and only after careful consideration of the current case.
  • Again, one of the core purposes of the Economic Base Technique is to determine those economic sectors that are export-based versus those based upon local conditions. In this case we have used a set of very basic assumptions to do this.
  • This general technique can be and should be modified in cases where other assumptions can be defended as correct. For example, at finer levels of detail within the SIC Code, certain services (like hotels or perhaps employment in the production of motion pictures) might be better identified as Basic Sector employment. In short, the analyst should willingly, but carefully deviate from the basic assumptions of this technique when it is clearly called for by local conditions.

Discussion Questions

  • What are the key assumptions of this technique?
  • Why do we assume certain industries are basic and others are non-basic? What is the logic behind these choices?
  • Do you see any problems with using the Assumption Technique? What limitations does this technique impose on the results?

References

Klosterman, Richard E. 1990. Community and Analysis Planning Techniques. Rowmand and Littlefield Publishers, Inc. Savage, Maryland. See Chapter 10.
Klosterman, Richard E., Richard K. Brail, and Earl G. Bossard. 1993. Spreadsheet Models for Urban and Regional Analysis. See Chapter XX.

Links

King County's Employment and Payroll Data (1994) by all SIC Codes from the US Census Bureau.
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