Park Equity Model

Graph breaking down the different criteria that was used to establish the information 

The Park Equity Analysis is built upon the US Census data analyzed at the Census Tract Block Group level, combined with statewide maps of public and local parks. The model prioritizes underserved areas of Maryland in need of park space by identifying areas with:

  • Low proximity to public park space
  • High concentration of children under the age of 17
  • High concentration of adults over the age of 65
  • High concentration of low income populations
  • High population density
  • High concentration of non-white population
  • High concentration of linguistically isolated population
  • High walkability of an area
  • Low access to transit

Each of these factors is represented in the model as a separate data layer. The layers include Census Tract Block Groups that are scored for the importance of these factors. The layers are added to produce a combined score for prioritizing the need for park space.

As a result of research that indicated the biggest indicators for poor access, the two layers that are double weighted for the model are the distance to parks and the percentage of non-white population.

Final scores are displayed in a quantile manner, categorizing block groups into five categories- measured against each other. Measurement scales are done by County- so the block groups from one county are not weighted against a county in another part of the state.

Defining Underserved Communities:

Part of the Park Equity model is devoted to the identification of underserved communities. This was done by defining the amount of children, senior citizens density, race, linguistic isolation and the average income of a Census Tract Block Group. Calculations were developed using the ratios below.

Ratio of Children: Ratio of the number of children age 17 & under relative to the total population. The higher ratio equals a higher score. (0-10).

Ratio of Seniors: Ratio of the number of adults age 65 & older relative to the total population. The higher ratio equals a higher score. (0-10).

Density: Number of residents per residential acres (as defined by urban lands in the 2002 Maryland Department of Planning land use/land cover data). Higher density equals a higher score (between 0-10) x 2.

Low Wealth Score: The ratio of household at or below 185% of the county poverty level. The higher ratio equals a higher score. (0-10)

Non-White Score: Ratio of non-white to white individuals in that census tract compared to the average ratio of the state. The higher ratio equals a higher score. (0-10).

Walkability Score: The Walkability Index Score is based on the US Environmental Protection Agency model which includes:

  • National Walkability Index (relative metric, higher values indicate conditions generally more conducive to pedestrian travel)
  • Employment and household entropy
  • 8-tier employment entropy (denominator set to the static 8 employment types in the CBG)
  • Street intersection density (weighted, auto-oriented intersections eliminated)
  • Distance from population weighted centroid to nearest transit stop (meters) but remember that significant transit capacity has been added since the date of source data used in this analysis (TRAX green line, extensions to other lines, FrontRunner south, etc).

Transit Access Score: The Public Transit Distance Score is based on the Accessibility Index from the United States Environmental Protection Agency. This is an index of the relative accessibility of a block group compared to other block groups in the same metropolitan region, as measured by travel time to the working-age population via transit. Higher values indicate more accessibility.

Linguistic Isolation Score: The Linguistic Isolation score is a measure of the number of households in which every member over the age of 14 speaks a non-English language and none speak English "very well".

Defining Access to Parks:

Access to park space was evaluated on the proximity to state, regional, and local parks and trailheads for public trails. This data was built from the Department of Natural Resources public lands geographic information systems (GIS) layer, and assembled local data from previous Local Parks, Recreation and Preservation plan data submissions.

Proximity to park space included those parklands outside of Census Tract Block Group and county boundaries and was calculated as an average of distances of each location in a block group to the closest park.

Combined Score:

The above factors were scored and then added together to produce a combined park equity score. Every Census Tract Block Group in the state was assigned a score of for a combined score. The park distance and non-white population fields are given a weight of 1, while the remaining 7 fields are each given a weight of 1/7.

Final scores are displayed in a quantile manner, categorizing block groups into five categories- measured against each other. The lowest score represents highest equity (low need) and the highest score represents low equity (high need).