What is Uexplore / Dexter?


Uexplore is a web application that provides access to the Missouri Census Data Center's public data archive, featuring U.S. Census and other public data. The interface allows you to navigate through the directories that comprise the archive and access files or subdirectories for further processing.

Files in the archive can be either database files (data tables comprising rows/observations and columns/variables in a special format) or non-database (mostly metadata, special navigational index pages, or sometimes raw data files) in a variety of common formats. Users can view and/or download most non-database files (in plain text, csv, xls, pdf and html formats) directly in their browser. However, when the user selects a database file, a special interactive web application called uex2dex is invoked. The uex2dex module generates a custom data extraction (Dexter) form.

The Dexter quick start guide provides a concise overview of the application, geared primarily to first-time users. To see what Dexter looks like, we recommend starting at the Uexplore home page and navigating your way to a dataset.

The data archive has been designed with the extract capabilities of Dexter in mind, so we do not have to have hundreds or thousands of separate files in order to provide the user with great flexibility for accessing data. For example, if we have a collection of data for all cities, states, and counties in the United States, we do not need to create separate sets for each kind of geography or one for each state. We can have a single large dataset that has variables whose values indicate what is being summarized: One such variable indicates the type of geographic entity (city, state, or county) and another identifies the state. With Dexter, it is easy to extract just the subset you need (e.g., just data for counties in California, or just state-level data for the entire country).

Data can be extracted into any of the following common formats:

Degree of Difficulty

How hard is it going to be for you to find and extract anything using Dexter? It really depends — on quite a few things. If you are a one-time user who just wants to extract a few numbers from the Census, then this is probably not the tool for you — at least not without assistance. This tool is aimed at a fairly sophisticated user, one who is willing to do extra reading and entering of codes and who is willing to put up with a bit of a learning curve in return for a fast and flexible access tool. There are certainly other applications which are more user-friendly, but sometimes at the expense of limiting you in what you can get.

There are three basic kinds of difficulty that you may experience when using this system:

  1. Difficulty with using the Dexter application, i.e. in understanding what a data filter is, and how to fill out the form to define one.
  2. Finding the data set(s) containing the data you need. Uexplore does not have a search engine. It is a simple data directory browser and is most useful when the user knows about the various data sources (e.g., knows about the difference between a summary file and a PUMS file).
  3. Understanding the details regarding the data sets once you have found the one(s) containing what you need. You are not likely to have much luck extracting just the data you want when you don't have a clue about the source data.

The first kind of difficulty — learning to use Dexter — can be overcome with a reasonable amount of effort. It would be comparable to learning how to drive with a manual transmission; it seems hard at first but once you get the hang of it, it seems almost as easy (and, some think, more fun) as the automatic. And you can go a little faster.

The second kind of difficulty is only overcome with experience or with the assistance that the MCDC offers in helping users find what they want (or perhaps to find that what they want does not exist, at least not in this data archive.)

The third kind of difficulty — understanding the data sets — requires some effort and patience. There are many different kinds of data, and users arrive with widely varying background regarding the data. If the specific data source being accessed is very complex (such as a decennial census summary file or a collection of ACS base tables) and the user has never worked with that sort of data, then there is a whole separate learning curve regarding what you can get and where it may be stored. The level of assistance that is available within Uexplore/Dexter varies with data collections. Some are much more well-documented than others, and many presume that the user comes in with some basic knowledge.

Users should keep in mind, however, that when they are overwhelmed by the complexity of the data, this is not a purely self-service web application. There are always links at the bottom of the page where you can contact someone with a question or comment. Use these and you may be pointed to the exact data set you need to be extracting from and told exactly which variables and/or tables need to be selected to get what you want. Or, as frequently happens, you can be informed that what you want is not something you can get — at least not from this archive. You may be pointed to an alternate source.

A good predictor of the degree of difficulty you are likely to have using this system is the extent to which you are already familiar with the way we have organized the archive into categories (subdirectories) called filetypes. These categories have mnemonic names such as sf32000x (standard extract based on the 2000 Census Summary File 3 data) or beareis (Regional Economic Information System data from the Bureau of Economic Analysis). In the ideal modern data archive, such categories would be invisible to most users. But this archive is geared towards researchers who have come to accept this way of organizing the data. The best way to start becoming familiar with these categories is to spend time carefully perusing the Uexplore/Dexter home page, where all these filetypes are listed with brief descriptions.

Detailed Metadata and Datasets Files

The biggest improvement we have made to the Uexplore/Dexter system over the years is in the development of a systematic way of providing access to more detailed and reliable metadata or documentation. This feature is implemented primarily in the form of special files (web pages) named Datasets.html, which have been added to most of our key most recent and important data directories. When you explore a directory with one of these files in it, you should heed the bolded desciption of the file displayed at the top of the page: "Use this custom data directory page to access the database files (only) with greatly enhanced descriptions and metadata."

The two major benefits of using the Datsets.html page as your guide are: The datasets are presented in a more logical order (not alphabetical by filename, as with the Uexplore directory page); and it provides links to special Details pages for many of the datasets. (You can also get access to these same detailed metadata pages (when they exist) by clicking on the Detailed Metadata link at the top of the Dexter query form.)

To Learn More

We have a series of online tutorials and help files to assist users with using the data archive with the Uexplore and Dexter web tools. See links to these modules (including this one) at the top of the Uexplore/Dexter home page.