The Difficulty of Data
As you’ll recall from our recent post, the city of Omaha is currently developing a Vision Zero Action Plan that will put Omaha on the road to eliminating traffic fatalities and severe injuries. One of the four core elements of Vision Zero is a “data-driven approach.”
SOS is also dedicated to data. Even Omaha’s Vision Zero Task Force made specific recommendations regarding data in 2019,
“Disaggregate data for traffic fatalities and serious injuries by race and ethnicity to allow for better analysis and to improve the ability to address potential equity concerns.”
The National Highway Traffic Safety Administration (NHTSA) says it best;
“Safety starts with crash data.”
What data can do:
Data on crashes can help law enforcement objectively decide where to locate traffic units.
Data on crashes can help engineers make sound design decisions.
Data can help researchers and municipalities create solutions well suited to a specific area.
Data can give lawmakers and citizens an accurate picture of the problem of unsafe driving
What data can’t do:
Data cannot always pierce the bias of politics. Take our home state of Nebraska as an example.
Forty eight states have distracted driving laws. All but three states have primary enforcement; Nebraska is one of those three states that only has secondary enforcement for distracted driving - which means the driver can only be stopped and cited for distracted driving if cited or charged with another offense.
For successive years, safety advocates and those impacted by distracted driving have tried to make distracted driving a primary offense in Nebraska. However, even with solid data, the bills didn’t leave committee.
LB 620 - 2019
LB 668 - 2016
LB 517 - 2015
LB 807 - 2014
No matter how objective and convincing data is, it is often defeated by incompetence or stubbornness.
Data is Difficult
So data is essential, and we want more of it, but there’s nothing simple or easy about data.
It takes
time,
effort, and
commitment
to collect,
analyze, and
present data in a meaningful and digestible way, ie graphs, charts, tables etc.
Data on Omaha’s Traffic Fatalities:
As of December 2, 2022, the Omaha Police Department had investigated 44 fatal crashes, as you can see in this tweet by an officer from the traffic unit.
However, the City of Omaha’s Fatal Crash Dashboard reports only 41 traffic fatalities - that’s 3 fewer deaths than OPD is presenting.
What’s the deal?
I contacted the City and received an answer plus some super interesting info on data:
Medical Condition Prior to Crash: One of the 44 fatalities involved a driver who suffered a medical condition prior to the crash where the cause of death was determined to be from the medical condition NOT the crash. Thus, OPD counted this as a traffic fatality but the city, which follows national guidelines for crash/fatality definitions, did not count it as a fatality on the Crash Dashboard.
Unborn Children: Two of the 44 fatalities recorded by OPD were both unborn children who were killed in crashes. The City of Omaha, along with the Nebraska Department of Transportation, follows national guidelines for definitions of crashes/fatalities where unborn children are NOT counted as a separate fatality from the mother. National standards consider a fetus to be part of a pregnant woman rather than a separate individual.
If you haven’t spent some time checking out the City of Omaha’s Fatal Crash Dashboard, I urge you to do so. At some point in the future, we’ll be able to access not just data on traffic fatalities but data on serious injuries as well. Since taking the position as Omaha’s Vision Zero coordinator, Jeff Sobczyk and others in the Public Works Department have been working hard to sort and analyze crash data - again, data requires time and effort.
You can also find crash data at the state level at the Nebraska Department of Transportation’s Crash Data site.
How Data is Presented
Once data is sorted and analyzed, it’s presented to the public. Always use a critical eye when looking at data and ask questions of the author if something seems confusing. Most honest and well intentioned researchers, journalists, etc will be generous, not stingy, with information.
Age Categories: For instance, when a chart was posted on Twitter a couple months ago with an age categorization similar to the chart below, people replied aggressively and claimed the data was “cooked” or manipulated because the age categories for youth were in 5 year increments whereas the older age categories were in 10 year increments. I have to admit that, at the time, I too thought this was strange.
I was curious about the age categories so I asked my favorite highway safety engineer at the Nebraska Department of Transportation. Here’s why the age categories differ, and it’s super interesting:
Additional categories for younger ages is likely due to the meaningful changes that occur in those populations. These younger people will make significant changes in both their “seat restraint type” and “position in the vehicle” as they grow older.
For example, children will go from being in a child car seat in the rear of the vehicle, then to a booster seat, then to a full seat belt restraint, then to front row seating, and finally into the driving position. All of these characteristics are meaningful factors in crash outcomes and thus are separated in the chart to display these differences.
Whereas older vehicle drivers and passengers in their 30s, 40s, or 50s don’t have the same transition and can be represented in larger groups.
A variety of ways to say the same thing:
In one of our recent newsletters we posted the October 2022 Traffic Fatality Toll from the State of Nebraska which stated
“only 53 of the 173 vehicle occupants killed during 2022 were using seatbelts.”
Tom Everson, founder of KKAD25, replied to our newsletter to say that another way to look at that data would be to say that so far in 2022, about 70% of traffic deaths in NE involved unbuckled drivers/passengers. This astounded me, and it astounded me that it had NOT occurred to me until Tom brought it up.
There is a variety of ways to present data. Such that the same info could presented in any of these ways:
53 of the 173 vehicle occupants killed were using seatbelts, or
120 of the 173 vehicle occupants killed were not using seatbelts, or
30.6% of the vehicle occupants killed were using seatbelts, or
69.4% of the vehicle occupants killed were not using seatbelts
All statements are accurate.
Ultimately, there are way too many people not wearing seatbelts, and as the data points out, they are dying at higher rates than those who do wear a restraint.
How do you see Data Now?
Do you see Data differently now than you did at the start of this article? Data will be a topic we continue to come back to, so let us know if you have any questions about data and traffic crashes. Don’t be shy, let your comment fly!
Special Thanks to the Following Folks: Nick Gordon (City of Omaha Public Works Traffic Division), Don Butler (Highway Safety Engineer with Nebraska Department of Transportation), Jeff Sobczyk (City of Omaha Vision Zero Coordinator), Tom Everson (Keep Kids Alive Drive 25), Eric Koeppe (President/CEO National Safety Council - Nebraska Chapter)
Cover Photo Image credit: National Cancer Institute on Unsplash