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What is a “Statistical Calculator”?
Presented by Doug Hillmer
Independent Consultant
What is a “Statistical Calculator”?
• Data Users need ways to assess statistical quality of estimates and derive statistical information from estimates
Ex. Which counties in Maryland and Northern Virginia have a median household income that is NOT statistically different from the median household income in Montgomery County Maryland? How do we identify local areas which should qualify for a government program aimed at brining more economic activity to depressed local areas? Has the percent foreign born population changed in a statistically significant way over the last 5 years?
• Covers tasks users have been doing on their own for a long timeEx. Creating new estimates from published estimates for a geographic area; creating estimates for a geo area of interest by combining geo
areas for which published estimates are available
• An SC tool makes it easier to do these tasks in a consistent mannerFormulas and processing steps should always be the same (unless a modification to the SC tool is announced)
• An SC tool relieves the user of the computational burden• How has the ACS played a role in the development of SC tools?• Should an SC tool be implemented as a spreadsheet app or a web app?• A brief history of the current effort to define requirements for an SC tool
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• Starting point for an SC tool – pre-aggregated sample data (i.e., estimates)• Contrast with creating a standard error for the initial estimates• Some of the basic SC tool functions:
- SE for sum of two or more estimates- SE for ratio of two estimates- SE for percent or proportion that one estimate is of another- Testing the difference between two estimates for statistical significance (at different confidence
levels)- Deriving an MOE at the desired confidence level from an SE
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What is a “Statistical Calculator”?
• How should an SC tool be implemented?
- Spreadsheet app (eg., New York State Data Center app, U. of South Florida app)- Web app (i.e., set of functions integrated into existing web app, such as AFF)
• Advantages and disadvantages of the spreadsheet approach
• Advantages and disadvantages of the web app approach
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What is a “Statistical Calculator”?
• Why we need a requirements document for an SC tool– Forces us to think about the functions that the tool must perform in great detail– Increases the probability that what is eventually developed really meets the needs of data users– Allows for improvements over time and revisions to the documentation over time
• Why we need an SC tool integrated with the app that contains the estimates– Reduces the chance of human error occurring– Allows for user help and guidance– Potential use of information available to the app containing the estimates
Ex. Which estimates in a data table may or may not be combined; which geo areas are overlapping or mutually exclusive, etc.
– Allows for adding new functions over time and immediately testing them in the larger app context
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What is a “Statistical Calculator”?
• Examples of what a web-based approach might look like • Sequence of web pages for one scenario
NOTE: The screen shots that follow are not meant to suggest any specific user interface design.
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What is a “Statistical Calculator”?
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• Next Steps for developing requirements for an SC Tool– Want to include other reviewers– Plan to do a webinar on the SC Tool idea later this Fall– Planning to hold a session on the SC Tool Requirements at upcoming SDC/CIC conf. at Census Bureau
• How to contact us and get a copy of the requirements if you want to participate in developing these requirements:
Send email to Doug Hillmer. [email protected] or Jane Traynham, Maryland State Data Center, [email protected]
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What is a “Statistical Calculator”?
