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2016-03-wapo-uber

Correction to "Uber seems to offer better service in areas with more white people. That raises some tough questions"

By Jennifer A Stark and Nick Diakopoulos

An Issue submitted by romelf#1 alerted us to a bug in our gatherUberData.py script (code copied from uberpy repository). We fixed the bug in October 2016, and collected a new Uber dataset, which is available here and here.

This is the default branch and contains all the files from the original Master branch, with a new UberSurgePricing_OSC.ipynb analyzing the new data. The original analysis and code can still be found in the Master branch.

Below we have detailed which values and statements from the Washington Post article have been affected by these changes to the code and new data collected. Importantly, the overall findings are unaffected by the new data: Better service is offered to areas with a greater proportion of white people. Statistical significance is stronger when the analysis is run with the new data, indicating that the bug introduced noise to the data, rather than creating spurious correlations.

Original Statement New statement
Some of the tracts most significantly affected by this race-related difference in service are labeled on the map above, including Congress Heights, Bellevue and Washington Highlands, and the southern part of Southwest D.C., where average wait time is almost seven minutes for an uberX." "Some of the tracts most significantly affected by this race-related difference in service are labeled on the map above, including Congress Heights, Bellevue and Washington Highlands, and the southern part of Southwest D.C., where average wait time is over six and a half minutes for an uberX."
"In contrast, the tracts benefiting from this race-related difference (majority white tracts with shortest wait time) include Dupont Circle, Logan Circle and Georgetown, where average wait time is just over four minutes." "In contrast, the tracts benefiting from this race-related difference (majority white tracts with shortest wait time) include Dupont Circle, Logan Circle and Georgetown, where average wait time is just over three minutes."
"These areas surge 43 percent of the time, which makes them attractive to drivers who want to earn more." "These areas surge 27 percent of the time, which makes them attractive to drivers who want to earn more."
"We found that tracts surged for anywhere from 16 percent to 47 percent of the time (see next map), with race also predicting how often tracts surge – even when accounting for differences in income, poverty and population density." "We found that tracts surged for anywhere from two percent to 32 percent of the time (see next map), with race also predicting how often tracts surge – even when accounting for differences in income, poverty and population density."
" The northwest part of D.C. illustrates this well with several colleges in the area, and an average wait time of just 295 seconds." " The northwest part of D.C. illustrates this well with several colleges in the area, and an average wait time of just 245 seconds."
"Despite having 75 percent people of color, Edgewood has an average wait time of 292 seconds, which is within the bottom quarter of shortest wait times. " "Despite having 75 percent people of color, Edgewood has an average wait time of 246 seconds, which is quicker than the average wait time of 275 seconds.. "

Below are detailed the original statistics using a generalized linear model for estimating both Mean Expected Wait Time and Proportion of time surging, and the new Robust regression for each estimation.

Estimating Mean Expected Wait Time coefficients (values in bold are statistically significant at p<0.05):

Predictor Original GLM New Robust Linear model
percent_POC_zscore 0.4805 0.53318
medianHourseholdIncome_zscore -0.1685 -0.1931
popDensity_zscore -0.4006 -0.2896
pecent_poverty_zscore -0.213 -0.1634
percent_POC_zscore:medianHouseholdIncome_zscore -0.1328 -0.2675
percent_POC_zscore:percent_poverty_zscore 0.3077 0.2133

Estimating Mean Percentage of Time Surging coefficients (values in bold are statistically significant at p<0.05):

Predictor Original GLM New Robust Linear model
percent_POC_zscore -0.5738 -0.6177
medianHourseholdIncome_zscore 0.3101 0.223
popDensity_zscore 0.3986 0.3607
pecent_poverty_zscore 0.3657 0.3518
percent_POC_zscore:medianHouseholdIncome_zscore 0.2128 0.2202
percent_POC_zscore:percent_poverty_zscore -0.1511 -0.2458

The maps shown in the article are also different. The original choropleth map for Mean Expected Wait Time (seconds) (left) and the new map (right)

original MEWT new map.

The original choropleth map for Percent Time Surging (%) (left) and the new map (right) original PROP new map.

The scatter plot charts shown in the article are also different. The original scatter plot of the relationship between proportion of POC and mean expected wait time (top) and the new chart (bottom)

original MEWT chart
new MEWT chart

The original scatter plot of the relationship between proportion of POC and percentage of time surging (top) and the new chart (bottom)

original PROP chart
new PROP chart

Below is the original README

This is a repository meant to support transparency and reproducibility of the data analysis and visualization presented in the Washington Post article "Uber seems to offer better service in areas with more white people. That raises some tough questions"

If you have cloned this repo and downloaded the raw [Uber data](NEW LINK), you can reproduce the analysis in this [notebook](NEW LINK).

The Data

Collecting data with the Uber API

Data were collected using the Uber API with config.config and gatherUberData.py - based on scripts of the same name from our uberpy project.

config.config was modified to collect data every 3 minutes, provided a list of 276 locations across DC, and provided a list of Uber API keys.

gatherUberData.py was modified to save data with the DC local datetime.

Sampling the Data using get_geographic_data.ipynb in Python2 (the only part requiring Python2) followed by Mapping_points_across_DC.ipynb in Python3.

The method for determining the 276 locations in DC to sample used the following steps:

  • A 22 x 22 grid of longitudes and latitudes was applied across DC
  • Addresses were then associated with each point using Nominatim from geopy.geocoders (installed with pip). Any point not in DC was removed.
  • Remaining addresses were then validated to require a house number and street prefix using address.AddressParser (installed with pip). This removed points that fell in the river or parks etc.
  • Remaining points were then checked against DC census tract IDs to make sure that each tract was represented.
  • Tracts not represented were added using the census tract centerpoints provided from the Tiger Census 2010 database using cenpy (installed with pip). NB that cenpy only works in python2.7
  • New tract center latitudes and longitudes were again address validated. Only 7 were not valid, and so those points were manually moved the smallest distance possible to a valid address.

These points were sampled every 3 minutes for 4 weeks from February 3 to March 2, 2016.

Data Dictionary

The following fields are available in the data download:

  • "timestamp" : string, Date and Time (EST) when API was pinged
  • "surge_multiplier": float, The surge multiplier for the current time and location
  • "expected_wait_time": integer, The number of seconds rider may have to wait between requesting a car, and the car's arrival
  • "product_type": string, The type of car -
  • uberTAXI
  • UberSUV
  • UberBLACK
  • uberX + Car Seat
  • uberX
  • uberXL
  • SUV + Car Seat
  • BLACK CAR + Car Seat
  • "low_estimate": integer, lower end of an estimated price of the ride (dollars)
  • "high_estimate": integer, upper end of an estimated price of the ride (dollars)
  • "start_location_id": integer, number between 0-275 that relates to our predetermined longitudes and latitudes across DC.
  • "end_location_id": integer, number between 0-275 that relates to our predetermined longitudes and latitudes across DC.

Requirements

If you use the Anaconda distribution, you're all set.

  • Python 3 (and python 2 only for get_geographic_data.ipynb )
  • ipython notebook / Jupyter
  • pandas
  • numpy
  • matplotlib.pyplot
  • scipy.stats (for pearsonr)
  • seaborn
  • statsmodels.formula.api
  • statsmodels.graphics.api (for abline_plot)

Funding

This project was funded by a grant from the Tow Center for Digital Journalism to study computational and data journalism in the context of algorithmic accountability reporting.

Feedback

Email Jennifer A Stark at [email protected]