Economic & Demographic Research Tools
All materials listed on this page are produced by Economic and
Demographic Research, Fairfax County Department of Neighborhood and
Some of the items below are available in Adobe Acrobat (.pdf)
format. In order to view the Adobe Acrobate files, you must have free
Adobe Acrobat Reader software installed on your computer. The
American Community Survey tools are Microsoft Excel files.
When estimates from Fairfax County and the Census Bureau are compared
they often differ. The estimates differ because different
methodologies and techniques are used to produce them. We have
developed some guidelines to help data
users determine which data source to use when comparing Fairfax
County data, Decennial Census data and American Community Survey
Combining Estimates and Calculating the Associated Margin of Error (MOE) Tool allows data users to combine American Community Survey estimates across categories or geographies and calculates the MOE for the combined estimate. For example, a data user may want to combine the estimates from several age categories.
Calculating Percents and the Associated Margin of Errors (MOEs) from Estimates Tool allows data users to enter American Community Survey numerical estimates and MOEs and transforms these estimates into percents. For example, a data user who combined age categories using the tool above may want to find out the percent and MOE of the total population this age group represents.
Statistical Significance Calculator When the difference between estimates is statistically significant it means that at a specified level of confidence there is a real or measurable difference between the values. It does not mean that the difference is large or important. This tool allows data users to measure the statistical significance between two American Community Survey estimates at three different levels of confidence - 90 percent, 95 percent and 99 percent. In addition, the tool calculates the associated confidence intervals for the estimates at these three levels of confidence.
Percent Change Calculator Tool calculates the percent change between two American Community Survey estimates and calculates the margin of error of the percent change.
Coefficient of Variation (CV) Calculator Tool calculates the associated coefficients of variation of a series of American Community Survey estimates and margins or error. The coefficient of variation is a relative measure of the variability of the estimate and is expressed in this tool as a percentage. The lower the coefficient of variation, the more precise and stable is the estimate.
Common Pitfalls in Conducting a Survey The intent of this brochure is to provide a brief review of potential problems that may occur during the survey research process.
Survey Questionnaire Design This brochure provides a brief guide to planning, developing, and testing a questionnaire for use in survey research.
Overview of Sampling Procedures The purpose of this brochure is to provide an overview of the sampling procedures available to a researcher. The differences between the various sampling procedures are discussed and examples are provided to illustrate the use of these procedures.