Lies, damned lies and statistics
“I can prove anything by statistics except the truth.” ― George Canning
“Facts are stubborn things, but statistics are pliable.” ― Mark Twain
“Definition of Statistics: The science of producing unreliable facts from reliable figures.” – Evan Esar
There are dozens of similar quotes about statistics. This is unfortunate considering that statistics, when used correctly, can paint us a clearer picture of reality that often contradicts our perceptions.
Alas, too many people use mathematics incorrectly. Sometimes it’s malicious, other times it’s out of ignorance. Either way, the results are the same: people are misled. Consequently, trust in statistics decreases.
The misuse of statistics is prevalent in the trucking industry.
For example, I recently wrote a story about Ohio’s truck parking information management system. Included in the story is the below video. Skip to the 50-second mark.
The narrator claims that “driver fatigue causes 87 percent of all accidents where the truck was the main cause.” This was news to me. In fact, the numbers I have read and reported on paint a completely different picture.
I reached out to the Ohio Department of Transportation to find out where they got those numbers. First of all, they didn’t. ODOT did not create that video. Rather, the video was produced by a consultant for the entire multi-state parking system, which can be found at TrucksParkHere.com.
With that said, I was given the following response from an ODOT spokesperson who reached out to that consultant:
“The original source of the 87 percent is an article from the Federal Motor Carrier Safety Association in July 2007. The article states that 87 percent of truck crashes are from driver-related causes. While not all of these crashes are related to fatigue, many of the subcategories could be fatigue related, and it is well documented that fatigue-related causes are under reported in safety data.”
In other words, the claim that (and this is a direct quote from the video) “driver fatigue causes 87 percent of all accidents where the truck was the main cause” is complete BS.
The stats do NOT say that at all. I cannot determine if this was malicious or ignorance. Perhaps both.
The more than decade-old study that was referenced is the Large Truck Crash Causation Study.
First, the word “causation” in the name of the study is a bit misleading. The study defines “causation” as “factors that are most likely to increase the risk that large trucks will be involved in serious crashes.” Not exactly causation.
Second, FMCSA’s definition of “large trucks” in the study is “trucks with a gross vehicle weight rating over 10,000 pounds.” That includes a wide range of vehicles in addition to tractor-trailers, including large pick-ups, vans, dump trucks, construction vehicles, etc. Considering that and the sample size of 1,123 large trucks that encompasses that wide range, it is hard to extrapolate much in regards to tractor-trailers specifically. Nonetheless, that is exactly what the video did.
Third, the Transportation Research Board’s analysis of the study confirms my suspicions. In TRB’s report, it determined the following:
“DOT cannot avoid these potential misunderstandings merely by avoiding the use of the word ‘cause.’ Any tabulations or discussions that highlight particular precipitating circumstances or occurrences (for example, the tabulation in the interim report of numbers of crashes by critical reason) will present the same problems of interpretation and will require the same careful explanation by DOT. Such tabulations are likely to be interpreted by many nonspecialist readers as indicating ‘cause’ or ‘fault.’”
In other words, the word “cause” can be misleading to the “nonspecialist readers,” like the contractor who produced the above video.
Let’s not forget the reliability of the specific stats cited by the video:
“We remain particularly concerned that the method of the present study is not well suited for obtaining reliable data on fatigue, driver inattention, and driver collision avoidance actions.”
Lastly, a 2016 study from the National Academy of Sciences determined this about the Large Truck Causation Study (emphasis theirs):
“Truck driver fatigue was found to be associated with 13 percent of the crashes (Starnes, 2006). This means that one of the drivers involved was found to be fatigued, but it was not established whether that fatigue was an important contributor to the crash.”
Not only does the contractor completely misrepresent stats from an 11-year-old study, but it also cites sections that are less reliable.
The truth is, determining fault or cause in any crash is extremely difficult. There is no reliable database that accurately determines such.
This is mostly because most police reports do not always determine cause. Furthermore, determining fatigue was the cause requires a judgment call in many cases.
There is a wealth of research that proves the need for parking that doesn’t include crash rates that blame truckers. Look no further than Jason’s Law Survey.
I’m the type of person who forms many, if not most, of my opinions and beliefs on empirical evidence and the scientific method. It is frustrating and disheartening to see the manipulation of statistics to support a narrative. It lowers public acceptance and increases public misinformation.
Whether we’re talking about the “driver shortage,” ELDs, hours of service, underride guards, you name it, the twisting of stats can be seen all over the trucking industry. If something does not seem right, find the source, do a little homework and determine for yourself if the numbers were presented correctly. After all, many people and groups rely on others to not do their homework.