Live data from Hacker News

Mapping Motor Vehicle Collisions in New York City

toddwschneider.com

11–20 of 28 posts

Re: Mapping Motor Vehicle Collisions in New York City

#11
The question is if the highlighted area are really more dangerous or if there are just more visitors. Shouldn't one take into account the traffic counts?

BTW: there is similar (open) data for Germany: https://unfallatlas.statistikportal.de/ (It clearly shows the problem I mentioned)

Update: sorry, it seems that this issue is already discussed in this thread

Re: Mapping Motor Vehicle Collisions in New York City

#12

The question is if the highlighted area are really more dangerous or if there are just more visitors. Shouldn't one take into account the traffic counts? BTW: there is similar (open) data for Germany: https://unfallatlas.statistikportal.de/ (It clearly shows the problem I mentioned) Update: sorry, it seems that this issue is already discussed in this thread

Yup. This is pretty much a map of population density in NYC.

Re: Mapping Motor Vehicle Collisions in New York City

#14
post #8

Earlier quoted context omitted.

Fatalities are a tiny minority of crashes and aren't really interesting to study because usually you basically wind up studying the behavior of drunk people and people who don't wear seat-belts and if you filter those out there's not much data left making meaningful conclusions hard to draw. Fatal accidents are often just normal accidents with a couple aggravating variables on top (e.g. person rear ends semi-truck in…

Drunk drivers and people that don't wear seat belts are still worth reviewing. While there are rarely engineering solutions to the fatalities that result, it can help inform education programs and initiatives. Amazingly, buckle-up and don't drive drunk advertising can make a difference.

I came of age at the end of the campaign making drink driving socially unacceptable in the UK to the point of being a social lepper if you drive drunk, even two or three drinks not falling about drunk - so it was normal to me that you don’t combine a night out with drink and your car.

I then moved to Texas where it was still just a ‘naughty boy’ type social offense until a major campaign that is still underway changed minds and hearts about it.

I’d like to see he stats in 10 years because it has been anecdotally very successful.

Re: Mapping Motor Vehicle Collisions in New York City

#15
post #8

Earlier quoted context omitted.

Fatalities are a tiny minority of crashes and aren't really interesting to study because usually you basically wind up studying the behavior of drunk people and people who don't wear seat-belts and if you filter those out there's not much data left making meaningful conclusions hard to draw. Fatal accidents are often just normal accidents with a couple aggravating variables on top (e.g. person rear ends semi-truck in…

Drunk drivers and people that don't wear seat belts are still worth reviewing. While there are rarely engineering solutions to the fatalities that result, it can help inform education programs and initiatives. Amazingly, buckle-up and don't drive drunk advertising can make a difference.

They absolutely are, but are rare enough that it's difficult to reach statistical significance when talking in the aggregate. That a particular part of town went from one fatality one year to zero fatalities the next year is probably not evidence of the success of any particular safety-related policy intervention, it's just noise. Studying all crashes provides a proxy that hopefully helps decrease the odds that the fatal ones will occur will making it possible to make robust, data-driven claims about success or failure.

Re: Mapping Motor Vehicle Collisions in New York City

#16
I've worked extensively with this dataset on a similar project, http://crashmapper.org, and through that process found that the data is extremely error prone. Perhaps 20% of the collisions recorded are not geocoded (e.g.lack lat, long coordinates) and don't contain other location information such as street, cross street, and zip code that could be used to geocode them. It appears that some precincts of the NYPD do a better job at recording a crash location then others. Even more of the data lacks values for "contributing factors" so it seems difficult to use as a metric for analysis. Often there is a mismatch between the total number of persons injured or killed and the number of pedestrians, cyclists, or motorists injured or killed. Furthermore, whomever maintains this dataset will periodically go back in time and update it seemingly at random, editing existing data or adding new data, potentially months or years back in time. Often it appears to be that the data maintainer is changing values for fields such as the number of pedestrians, cyclists, motorists injured or killed. Presumably this is because more information surfaced about an incident at a later point in time and the city must go back and update it. However this can result in stats from the data not aligning with the NYPD's or DOT's official stats from a previous year. I would advise anyone to keep these facts in mind if trying to use the data for analysis and policy recommendations, such is open data.

Re: Mapping Motor Vehicle Collisions in New York City

#17
post #8

Earlier quoted context omitted.

Drunk drivers and people that don't wear seat belts are still worth reviewing. While there are rarely engineering solutions to the fatalities that result, it can help inform education programs and initiatives. Amazingly, buckle-up and don't drive drunk advertising can make a difference.

They absolutely are, but are rare enough that it's difficult to reach statistical significance when talking in the aggregate. That a particular part of town went from one fatality one year to zero fatalities the next year is probably not evidence of the success of any particular safety-related policy intervention, it's just noise. Studying all crashes provides a proxy that hopefully helps decrease the odds that the f…

On a project I am currently working on, we saw pedestrian fatalities shift from 7 to 13 in consecutive years. it is a nearly 100% increase but like you said, it is just noise. This is in a city with around 100,000 residence. Convincing politicians that it is just noise is a whole different story.

Re: Mapping Motor Vehicle Collisions in New York City

#18
post #13

https://xkcd.com/1138/

To be fair, they mention that in the first paragraph after they introduce what the data is actually doing.

There is still a value to looking at a population-correlated heatmap in order to draw conclusions from the discrepancies between the two.

Re: Mapping Motor Vehicle Collisions in New York City

#19
Having done something similar for the Long Beach, CA area in college, one of the most interesting takeaways was the relative spatial distribution between fatal and non-fatal accidents.

Non-fatal accidents clearly clustered around high traffic areas, but fatal accidents didn’t reveal the same clustering. Instead they appeared to be uniformly distributed across the city.

I’m sure there is an explanation in this, and this was only 10 years data for a single city, but it always felt a little spooky that these accidents were equally likely to happen anywhere (though most likely later in the night).

Post reply on HN