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ACS Profile Reports: Usage Notes

Rev. 01/22/2011
What's the Difference    Header Lines General Layout Showing Statistical Reliability
Charts Indentation in Subject ColDownloading the Data Using Front End Menu
Related Apps Alternate Front Ends
Return to the ACS Profiles web application.

What's the Difference

These reports represent the Missouri Census Data Center's attempt to distill the most frequently accessed data items from the Census Bureau's American Community Survey summary data products. American FactFinder web site users will be familiar with the ACS-based Data Profile reports on that site. These reports obviously are modeled after those Bureau products. (The source of most of the data used in these reports is the xls (or csv) file with Data Profiles data distributed by the Census Bureau.) But the MCDC profiles do differ in significant ways, in terms of both form and content. Some key differences:

  1. The MCDC profiles allow the user to select up to 4 geographic areas and will display the data for those areas side by side to facilitate comparison.

  2. Statistical reliability of the data are displayed here using a 3-tiered font weighting scheme with MOE-based values (relative MOE's and confidence intervals for counts; MOE values for Percents) accessible by holding the mouse over any data item on the report for 1 second. (See details, below).

  3. These profiles will always provide both a count and a percentage measure whenever possible. So (for example) while the Bureau profile shows only poverty rates, our profile displays both counts and percentages of poor persons (or families, etc.)   Note: Since this note was written the Census Bureau has modified their profiles so that they almost always now include both counts and percentages (except for the data on poverty).

  4. You can choose to view multiple profiles at once here. You can only display one Bureau profile at a time (i.e. Social, Economic, etc.)

  5. The data used in these reports are stored in datasets that can be accessed and downloaded (using our Dexter web extraction module). You can easily access these data for every geographic area in the country in a single query. Profiles on the Bureau web site only provide access to the data one geographic area at a time.

  6. These tables provide links to dynamically generated color charts for visualizing the data in a table.

  7. "Drill down" links are provided to allow viewing of detailed "parent" tables which contain (usually) more detailed data that what are shown here

  8. On the other hand, the Bureau provides a "Narrative Profile" option where you can see highlights of the profile data in a non-tabular fashion, interspersed with a data charts. This option is not available with the MCDC application.

Our Ten Things to Like About the Missouri Census Data Center's ACS Profiles is a "Top Ten" list that shows and tells about some of our favorite features of this application It was created as a powerpoint presentation and converted to this pdf file. (A companion document has the same slide content but also contains speaker notes.)

Header Lines

These reports contain two header lines. The first is constant - "ACS Profile Reports 20<yy>"; the second identifies the (primary - i.e. first chosen) geographic area being summarized. It begins with the name of the area (if applicable) and then the standard geographic code for the area. This is the geoid code used by the Census Bureau (although not always visible to the user) in their AFF databases. It is comprised of a 3-digit geography type code (040 for a state, 050 for a county, 160 for a city, etc) followed by a 2-digit geographic component code (usually "00" to indicate "not a geographic component"). The letters "US" separate the first 2 codes from the FIPS code(s) that follow. The geoid code for the city of Columbia, MO is 16000US2915670 . The 7 digits following "US" include the FIPS state code (29) and the FIPS place code (15670).

General Layout of Tables

The report is really a series of up to 4 broad-subject-category profiles: Demographic, Economic, Social and Housing. The user can opt to display any subset of these 4 profiles. Those chosen will appear in the stated order (with Demographic first and Housing last on the page). Each profile is preceded by a bold header line identifying it. There is a menu bar across the top that allows you to go directly to any of the sub-profiles.

The reports are broken into a Subject column, one to four Number-Percent column groups with the name of the area being summarized displayed in the over-arching first header row. The order of the geographic areas left to right across the page is determined by the order in which you select them (or in which they were selected for you if you came in directly from a web link). A final column at the far right of the report labeled "Base Table(s)". In some rows you will see the name of a base table used as a hyperlink. The table referenced contains more detailed data related to the current data item (and in some cases is the source of that data item). A click on one of these base table hyperlinks invokes an application (called acstabgen) that will display that table for each of the geographic areas currently selected. This amounts then to a kind of demographic "drill down" for more detailed information.

The lines of the table consist of Table Header lines identifying the subject matter and "universe" (i.e. the kind of entities being counted or measured). These are highlighted with a gray background. The first table header line is a hyperlink to the metadata where you can get more detailed information about the variables in that table. The detail lines of the table are divided into columns. The Subject column identifies the data displayed on the line. Indentation is used to indicate subordinate data. For example, in Table 24, "Owner Occupied Units" is indented within "Occupied Housing Units". Typically, the first detail line in a table contains the total universe count and is displayed in bold. All items that count or measure the entire table universe are left justified and bolded.

The Number columns contain a count or other measure (mean, median or occasionally a percentage). The Percent columns are filled in if and only if the item is a count. It is usually (but not always) a percentage of the next higher level count. (To see for sure what denominator was used to calculate the percentage follow the table-header link to the metadata and locate the row for the current data item; the "Universe" column contains the name of the variable used as the denominator.)

Showing Statistical Reliability of Numbers (MOEs)

These reports use two methods for helping users understand the statistical reliability of the numbers. The first involves using heavier or lighter fonts to display values which are deemed as notably reliable or unreliable. The datasets used in generating the reports include a margin-of-error (MOE) item for each variable provided by the Census Bureau. We use these MOE values to calculate a relative MOE value, defined as the MOE as a percent of the numeric estimate. For example, for the state of Missouri for 2006 the variable MedianRent had a value of 607 with a corresponding MOE value of 6. This yields a RMOE (relative MOE) value of 1% (6 as a percent of 607). Obviously, a pretty reliable number. Whenever we display a value we use a bold font if the RMOE for that item is less than 15%; if it is 35% or greater we display the value in a light gray to make it somewhat hard to read. Finally, when the RMOE is in the 15-34.9% interval we display it with a normal weight font in black. (The corresponding Percent column value is displayed with the same font/color as the Number value.) If the user moves the cursor over a data item in the report and leaves it there for 1 second a pop-up box will appear to display reliability information in the form of the RMOE and the confidence interval (if this does not work make sure your browser window has focus by clicking within the window and then trying again). The bounds of the confidence interval are derived by simply subtracting and adding the MOE value to the estimate (and, in most case, making sure the lower bound does not go below 0). Similarly, if the cursor is placed over a Percent column item for 1 second a pop-up box will display the MOE for the value, expressed in percentage points. For example, if a Percent value is 12.5 and the pop-up box displays "+/- 0.9" it means that the 90% confidence interval for this item is 11.6 to 13.4.

The Census Bureau, along with most statisticians, prefer to use the Coefficient of Variation (or "CV") statistic as the relative measure of statistical reliability. The CV is defined as the SE (standard error) as a percentage of the estimate. The SE can be easily derived from the 90% level MOE using the formula:
SE = MOE / 1.645
So the difference between the Relative Margin of Error measure that we use and the CV is simply:
CV = (MOE/1.645)/E = RMOE/1.645 (where E is the estimate and RMOE is the relative margin of error)
So the intervals we use to determine our 3-tiered font scheme can be expressed in CV terms as:

  • Bold font when CV is < 9.1 (15/1.645)
  • Plain font when CV is between 9.1 and 21.2 (35/1.645)
  • Light gray when CV exceeds 21.2

Charts

You will see this chart icon in the upper right corner of most of the tables. Click on these icon links to display charts associated with the tables. They will be dynamically generated and will pop up in a new window. You need to have the Adobe Flash Player application installed on your PC in order to view the charts. We suggest closing these windows before going back to display more, since they will be displayed in the same window and it may not pop up if it is already open. (The chart may be displayed but in a window that is not automatically made visible - you could still view it by clicking on its entry in the task bar.)

Indentation in the Subject Column

Indentation is used to indicate qualifying of categories. For example in Table 4 the 4th line is labeled "White alone" and is indented within the previous "Not Hispanic or Latino" line. Thus this item is the count of persons who are not only white alone but are also not Hispanic. The following 4 items in this table are at the same indentation level, indicating that they are counts of categories that include being non Hispanic.

Downloading the Data

At the bottom of the report you will see a row of hyerlinks to related pages. The third link is "Extract Data via Dexter". This refers to the MCDC's
Dexter web application for accessing our data collection. This hyperlink bypasses the usual explore-the-directory phase of accessing a dataset, and takes you directly to the dexter (data extraction utility application) first screen with the appropriate dataset already selected. The page includes a link to the Dexter Quick Start Guide, appropriate for first-time users, as well as to more detailed online help for using the application. You may need to specify a filter to avoid getting data for the entire dataset (this would typically involve coding a filter based on SumLev and/or State variables.) Dexter also allows you to select variables, so you do not have to take the entire 950 variables (more or less -- it varies slightly with geographic level). Using this tool it would be very easy (for example) to generate a csv file containing just the geoid, Areaname and MedHHIncome variables for all available cities (or counties, or PUMAs, or Congressional Districts) in the entire US (or for one or more selected states.)

Using the Front End Menu

There are a number of ways that users can come to this application, but one of the most common is to get here by accessing the
front end menu page for the application (this is where you go if you choose the ACS Profile Reports option form the Quick Links menu box on most MCDC web pages, for example.) We have tried to make this page simple and intuitive but it never hurts to tell people what they can expect and what they can and cannot do.

The application will display profiles for up to 4 geographic areas for a single ACS time period (year or years).

There are three drop-down select lists across the top of the ACS Profiles Menu page. Use the one on the left to first choose the ACS time period. We have made "2005-2009" the default but you can easily change the selection to get either single or 3-year period estimates (which will mean fewer geographic areas to choose from), or you can choose to select data for earlier time periods going back to 2006. You need to make this choice first. If you make choices off other menus and then go back and change the Time Period, all your other choices will be lost and you will be starting over.

The middle select list allows you to choose a state. This is relevant when you select an Area Type (the rightmost select menu) that is a sub-state geography such as place, county or census tract. Notice that Missouri is the default choice; so if you go straight to choosing Area Type and select Counties from that list you will get to be presented with a list of Missouri counties. If this is not what you want, simply go back and choose your state off the middle select list. Then you will need to repeat your choice of Area Type.

Each time you select an Area Type value the application will fill the selection box at the lower left with a list of all the geographic areas of that type for the chosen period and state (if relevant). You then can click on the entries in this box to specify that you want to see data for them. Each time you click-select an area it should appear in the "Selected Areas" box on the right. Once you have selected an area you cannot unselect it by itself, but you can use the "Clear Cart" button to start your selection process over. Note that you can make selections from multiple Area Types and multiple states. But you can not choose from multiple time periods. If you change that choice, everthing gets reset and you are essentially starting over.

The profile report is actually broken down into a set of 4 sub-profiles: Demogrpahic, Economic, Social and Housing. Just below the two geographic select boxes you should see a row of 4 checkboxes corresponding to the 4 sub-profiles. Uncheck any of the 4 that you are not interested in seeing. Finally, click the Generate Report button to indicate that you are finished making choices and want to see a report. The report should be delivered in less than five seconds (less than two on most days, but it can vary with your choices). After viewing the report in your browser (with the option to capture the results as a pdf or xls file) you can user your browser's Back button to return to the ACS Profiles Menu page. None of your choices you will be "remembered" upon your return.

Note that the order in which you make your AreaType-Area selections will be the left-to-right order in which the data for these areas are displayed in the report. The first area selected will also have its name included in the report title and will be used as the area for the link to Related Applications as we shall now explain.

Related Applications

For most geographic levels there will also be a hyperlink at the bottom of the report labeled "Related Applications". This link will take you to the "applinks" web utility which will allow you to choose from a menu of other reports/applications available for the current (first chosen) geographic area. For example, you will be able to link to the corresponding "dp3_2k" report (SF3-based profile) and a comparable report based on 1990 census data (for many, but not all geographic areas nationwide). A few of these applications will only be available for Missouri or other limited universes.

Note that this link can be used to view an ACS profile for the current geographic area (the first one chosen if you have more than one) for a different period (of the same vintage, if available). So if you are currently looking at a 5-year period profile you can click on related apps and follow links to either 1-year or 3-year periods, if available. Since applinks will only direct you to the latest available data for that period you cannot go back in time using this link (e.g. you can't go from a 2007-2009 profile to a 2005-2007 profile for the same area.

Alternate Front Ends

Most users will use the ACS Profile Reports Menu application to choose their options (time period, geogrphic areas, sub-profiles) when generating a profile report. But those users who are comfortable with things like URL's and cg-bin apps and techie stuff like that will appreciate the fact that the result of all those menu choices you make can be encapsulated into a custom URL. For example, on the menu page you should see a link near the top of the page to "Sample Report". If you click on that you will soon see an ACS Profile Report displayed in your browser that has all 4 of the sub-profiles being displayed for 4 different geographic areas (a city, a county containing that city, the state containing that county and the U.S. Totals. Those of you who know what the Address box is on a browser display are instructed to look at what is displayed there when the sample report is being displayed. It looks something like this:

http://mcdc1.missouri.edu/cgi-bin/acsprofiles/acsprofiles.py?period=2005_2009&geoids=16000US2915670&geoids=05000US29019&geoids=04000US29&geoids=01000US&subjects=Demographic&subjects=Economic&subjects=Social&subjects=Housing.

Gobbledy-gook? Perhaps, but not really as bad as it might first appear. The first part
http://mcdc1.missouri.edu/cgi-bin/acsprofiles/acsprofiles.py
just tells the browser where to find the program ("app" for those of your under30) to be invoked.

This is followed by the "parameter specifications" portion. Each of these "parm-specs" is of the form
&<parmname>=<parm-value> where <parmname> means substitute the name of the parameter, such as period or geoids and <parm-value> means substitute some value to be associated with that parameter. So the "parm-spec"
&period=2005_2009
is just the secret code needed to tell the application that we want the 2005 to 2009 5-year period data. If the value had been 2009 instead of 2005_2009 then the program would have understood that what was wanted was single year data from 2009. There are 4 parm specs using the same parameter name geoids. That is how we tell the application that we have 4 geographic areas that we are wanting to see data for. The values of these geoid parameters correspond to the values of the geographic identifier values stored with the ACS data. The geoid value specifying that we want Columbia, MO is 16000US2915670. Breaking this down: "160" is a summary level code that indicates a Place (city) summary; "00" means that it is not a geographic component summary, while "US" just says it is a United State geogrphic area. "29" is the FIPS state code for Missouri and "15670" is the FIPS/ANSI code for the city of Columbia. It is not all that hard to see the pattern for these IDs.

The point of all this is that these URLs are the kind of thing that web developers can take advantage of to create their own custom menu pages that can lead users to custom profile reports without any need to go through making a series of choices off a menu. It might take 15 or 20 seconds to choose the 4 geographic areas used on our sample report. But someone who wanted to provide comparable reports for all cities of a certain size in a certain state could pretty easily figure out how to generate the URLs to do so and put those on a page with city names as the hyperlinks.
To be continued....

Return to acsprofile web application.

This file last modified Saturday January 22, 2011, 09:53:15


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