jradack / zip_hospital_distance

Hospital - ZIP Code Distance Project

Code and data for project calculating the distance and drive times between maternal delivery hospitals and maternal residence ZIP codes.

Code

• centroids_distances.r: Computes and analyzes the distances between weighted and unweighted ZCTA centroids.
• distance_matrix.r: Computes the long-form (Haversine) distance matrix between ZCTA centroids and hospital addresses. The output dataset is fed to the script for querying the googlemaps API.
• distance_matrix_hospital.r: Computes the long-form Haversine distance matrix between hospital addresses within the same state.
• function.r: Contains all of the R functions used within the other R scripts.
• googlemaps_request.py: Makes the API calls for driving/transit distance and time between ZCTA centroids and hospital addresses.
• merge_zip_codes.r: Merges ZIP code information to the distance matrices with google maps data.
• plot_map.r: Maps ZCTAs and their centroid.
• pop_weight_centroid.r: Computes the population-weighted centroids for 2020 ZCTAs.
• state_query_count.r: Counts the number of queries would be needed at varying levels of geographic complexity.
• zcta_block_group_cw.r: Checks if census block groups map uniquely to a ZCTA.
• zcta_cbsa_cw.r: Creates a crosswalk between ZCTAs and core-based statistical areas (metropolitan and micropolitan statistical areas).
• zip_code_prefix_scrape.py: Scrapes the Wikipedia page with a table that crosswalks three-digit ZIP code prefixes to states.

Hospital - ZIP Distance Matrix

To generate the distance matrix output from scratch, run the scripts in the following order:

1. pop_weight_centroid.r
2. distance_matrix.r
3. googlemaps_request.py
4. merge_zip_codes.r

Hospital - Hospital Distance Matrix

To generate the distance matrices between hospitals within the same state, run the script distance_matrix_hospital.r.

Data

Raw Data Files

The following raw data files are not included in this repository.

• AHA birth hospital addresses
• National ZCTA - census block crosswalk from the Census Bureau.
• State-specific shapefiles for census block from the Census Bureau.
• Core-Based Statistical Area shapefile from the Census Bureau.
• ZIP Code - ZCTA crosswalk from UDS Mapper.

Hospital - ZIP Distance Matrix Data Dictionary

There are two versions of the distance matrix file for each state - one without the Google maps columns, and one with the Google maps columns. The same hospital - ZCTA pair may be represented multiple times in a file since multiple ZIP codes mapped to the same ZCTA in the crosswalk. If the value for any of the Google maps columns is -1, this means that Google maps could not find a valid route between the two requested locations.

Overall columns

• state: (chr) 2-letter state abbreviation
• fips_state: (chr) 2-digit state FIPS code
• year: (int) Year of the hospital address
• hospital_id: (chr) AHA ID of the hospital
• hospital_latitude: (num) Hospital latitude
• hospital_longitude: (num) Hospital longitude
• zcta_geoid: (chr) 5-digit ZCTA GEOID
• zip_code: (chr) 5-digit ZIP code matched to the ZCTA
• zcta_latitude: (num) ZCTA centroid latitude
• zcta_longitude: (num) ZCTA centroid longitude
• haversine_dist_m: (num) Crow-flies (Haversine) distance between the ZCTA centroid and the hospital address, in meters

Google maps columns

• distance_driving_m : (num) Google maps driving distance in meters
• duration_driving_sec : (num) Google maps driving time in seconds
• distance_transit_m : (num) Google maps transit distance in meters
• duration_transit_sec : (num) Google maps transit time in seconds

Hospital - Hospital Distance Matrix Data Dictionary

The distance between two hospitals is symmetrical, and the labeling of source and destination hospitals is out of completeness and convenience for merging/filtering.

• src_hospital_id: (chr) AHA ID of the source hospital
• dest_hospital_id: (chr) AHA ID of the destination hospital
• haversine_dist_m: (num) Crow-flies (Haversine) distance between the two hospital addresses, in meters