2  Start Here!

This chapter is written to be the starting point for using the Spatial Equity Data Tool either via the web tool or the API. The tool is flexible and allows users to perform numerous different types of analysis. Consequently, there are many options a user can choose from when developing an analysis for the tool to run.

This chapter outlines six key decisions a user should make when using the tool. It also links out to chapters that cover each of the issues discussed here in more detail.

Resource Data

Broadly, the tool currently takes point spatial data (think anything that can be plotted on a map as a set of points). More specifically, data inputted to the tool must be in the form of a comma separated values (CSV) file. CSV data must satisfy the following requirements:

  • The file must have column headers in the first row.
  • Two columns must correspond to longitude and latitude (in the EPSG:4326 or WGS84 coordinate reference system).
    • If you do not know what CRS your data is in, the tool makes the reasonable assumption that it is in EPSG:4326.
    • If the data have a published CRS that is not ESPG, you convert the data to have CRS EPSG:4326.
  • The data file must be smaller than 200 MB.
  • The geographic point locations must be from the US (50 states plus the District of Columbia).
  • The file should use UTF-8 encoding.

If data do not conform to this format, a user should preprocess them to fit these requirements.

For more details, see Chapter 3.

Geographic Scale

The tool conducts analyses at one of four scales:

  • National
  • State
  • County
  • City

We recommend determining which scale to use depending on the geography your data cover. For example, if your data cover a specific city, use the city scale. If your data come from a single state, use the state scale.

For more details, see Chapter 5.

Baseline Datasets

By default, the tool compares the uploaded resource data against numerous demographic groups in both the demographic and geographic disparity scores. To select which of these default groups to use in their analysis, users should consider the target or impacted population for the uploaded resource data. For example, if a user uploads a dataset with playground locations, they may consider children to be the appropriate target population and select children as the baseline population for the demographic and geographic disparity scores.

For a list of the demographic and geographic comparison datasets built into the tool, see Chapter 4.

If a user determines the most appropriate baseline population is not included among the defaults, they should consider adding a supplemental demographic or geographic comparison dataset. The API gives users this functionality. For more information, see Chapter 10.

Filters

The web version of the tool allows users the option to filter their data before running analyses on it. This means that users can drop certain records they hope to exclude from analyses. Users should use this feature to exclude records that are not relevant to the analysis they are conducting.

Users of the API should filter their data on their own before submitting it to the API.

For more details about filtering, see Chapter 6.

Weights

Users can weight the point resource data by a specific column in their dataset. This option is useful if each point contributes a different amount to the overall distribution the user seeks to analyze. For example, it could be reasonable for a user to weight their analysis of the distribution of public bike share stations by the number of bikes provided by each station.

For more details on weighting, see Chapter 6.

Travel Sheds

The API allows users to use walk or drive travel sheds for analysis. Using this option, all resource data points within the shed, not the tract itself, are deemed accessible to the point. Users should consider what constitutes reasonable access to their resource data, and if this differs dramatically from the census tract in which a resource is located, they should consider using a travel shed.

Please note that this functionality is an advanced option and should only be used by experienced tool users. It is available for cities and counties in Maryland, Washington, D.C., and Virginia, is still in “beta” version, and changes the interpretation of the results. For more details on travel sheds, see Chapter 19.