Citi Bike & Subway - A Preliminary Study

According to the previous sections about the growth of Citi Bike in terms of usages, racks, and membership, we assume that a number of people use Citi Bike as a regular method to commute for the last few miles of journey to work places or somewhere else. Now we take a look at Citi Bike as a role for commuting method in the city.

Given not everyone is living in Manhatan, there is a typical scenario that a gentleman living in Queens takes subway to Manhattan midtown and then rides Citi Bike to his office 2 miles away everyday. So we looked into Citi Bike’s relationship with other transportation distribution, to be more specific, the subway station density.

From the leaflet map we can see that according to the seasonal data, the highest usage of Citi Bike is always around Mid/Downtown across 2016, where also has a cluster of subway stations, regardless of Citi Bike’s expansion in the second half of the year.

The start of Citi Bike riding seems to have a significant positive correlation with the clustering of subway stations on neighborhood level. However the result does not reveal the causal effect between the two variables, so further research is needed for a more solid result.

We used QGIS and GeoDa to study the spatial clustering effect of Citi Bike riding. The graph below shows the relationship between Citi Bike usage clustering and subway station presence. The red spots are high-high cluster, and the green ones are low-low cluster, while the white spots do not show significant clustering effect.

We can see that the high usage cluster is exactly where the subway density is the highest around Midtown and Downtown Manhattan.

However it??s more like a preliminary study because we only checked the correlation, but did not reveal the causal effect between the variables. Since midtown and downtown are the busiest place in NYC, the correlation may be due to some kind of other spuriousness. The next step of this study is to control more variables and consider the potential overlap of peak time of both the Citi Bike and subway.