1 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 time Ex. 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 manner Formulas 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 2

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 3 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 4 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 5 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. 6 What is a “Statistical Calculator”?

7

8

9

10

11

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 to Doug Hillmer. Jane Traynham, Maryland State Data Center, 12 What is a “Statistical Calculator”?