Monthly Archives: March 2019

No room for human error

Jaskirat Singh Sidhu caused the bus crash in Saskatchewan that killed over a dozen people. It’s a tragic event that received lots of media attention, in Canada, and elsewhere. The judge of the case recently handed Sidhu an 8-year prison term as punishment for causing the crash. A public transcript of the judgement can be found here.

Here is a list of important facts concerning this case.

  1. Sidhu pleaded guilty to causing a collision that killed 16 people and injured 13. Specifically, he pleaded guilty to 16 counts of dangerous driving causing death, and 13 counts of dangerous driving causing bodily harm. These are criminal code offences in Canada, with a maximum sentence of 10 years in jail.
  2. Sidhu expressed remorse, and there is no evidence of any intent to have caused this collision.
  3. There were multiple stop sign warnings indicating that Sidhu was required to stop at the intersection.
  4. The visibility was not an issue (due to weather or time of day)
  5. Sidhu was not speeding at the time of the collision.

Here is some other information that is not specific to this case, but is important for context, and available to anyone who cares to look.

  1. Many drivers have driven through stop signs and other traffic controls. If your personal experiences don’t convince you of this, the empirical evidence is abundant. In a U.S. study a few years ago, 13% of drivers at a stop sign controlled intersection did not stop at all and 52% came to only a rolling stop [1]. Older data from Canada showed similar numbers [2]. In a 2009 study of older drivers in the US, almost 16% of drivers over 66 years of age failed to stop at a stop sign at least once over a 5 day period [3]. Stop sign violations are second only to speeding violations on a per-kilometre-travelled basis [4], and are responsible for between 5 and 10% of collisions involving casualties [5].
  2. Stop signs are not as effective as common sense might dictate. Multiple signs might even be counter productive, and changing controls from yield to stop may even increase risk of motor vehicle collision [7]. Some have argued that signs are a distraction, that we may become desensitised to them the more of them that there are, and we’re better off reducing the number and size of traffic controls [8,9].

On balance, this information shows that humans make mistakes–both in missing or ignoring traffic controls, and in assuming that traffic controls necessarily increase safety. Sidhu’s responsibility for the collision is not in question; what is in question is what punishment is appropriate when someone makes a fairly common mistake that leads to an incredibly unlikely and tragic outcome?

The judge’s view is to punish him with a jail sentence of 8 years. This is below the maximum. My gut tells me this is unfair, but I am not a judge, so I’m not sure my gut matters.

However, I do take exception with some of the reasoning offered by the judge. In her sentence ruling, the judge argued that it was “baffling and incomprehensible”  that Sidhu missed the stop signs that were posted. As noted above, it should be neither baffling nor incomprehensible to anyone who cares to consult research on the efficacy of stop signs, or reads local newspapers [10].

Humans make mistakes. Sidhu’s mistake was not unique, not uncommon, and not malicious. What was uncommon was the convergence of other facts surrounding this event–that a bus full of teenagers happened to be in the wrong place at the wrong time.

The fact that the judge was motivated to sentence him to 8-years at least in part because she can’t imagine how a person could not have seen the stop signs is simply ignorant. It is clearly possible for a person to make this kind of mistake, as well as a variety of other perceptual and judgement errors that leads a person to run through a rural intersection without stopping. It happens all the time.

Another problem I have with the reasoning of the sentencing seems to have been the magnitude of harm. In her decision, the judge writes “a sentence of more than six years is mandated due to the horrific consequences of his actions.”

On the one hand, the judge acknowledges that Sidhu had no intent to harm, but was simply very negligent and inattentive. On the other hand, she is holding him responsible for the gravity of the outcome; had he been equally inattentive but killed one person, it seems that he would have received a shorter sentence.

In legal circles this may make sense, but to me it seems illogical. Sidhu’s crime was dangerous driving, and his dangerous driving directly increased the probability of causing a collision. He is accountable for that. However, this increase in probability had no corresponding impact on the consequences once a collision occurs; the bus full of young hockey players would still have been at that intersection whether or not he stepped on the brakes in time to avoid the collision.

Obviously the bus driver and victims of the collision were not at fault here. But assigning fault to Sidhu that is proportional to the loss of life suggests that he was responsible for the severity of the consequences, in spite of him having no control over them. I’d understand this conclusion if the judge ruled that he intended to cause the collision. However, she accepts that Sidhu “did not deliberately drive through the intersection.”


Something in me is unsettled by the fact that Sidhu is being punished harshly partly because of the number of lives lost in the this tragic event. He was negligent, and punishment may be required, but was he really so much more negligent than the average truck driver, or even the average person?

I’d like to think all of us can relate to making mistakes. I guess we should just feel lucky that most of our mistakes are very unlikely to harm anyone, as it seems that the courts have little tolerance for human error.

Immunization and Web 2.0

We just published a new article related to vaccine content on YouTube:,60n7a2G8

This research started as part of an honours thesis by Monika Chase, an undergraduate student in the School of Interdisciplinary Science. We expanded this work and turned it into a paper exploring vaccine related content on YouTube.

Our objective was to compare sentiment (measured by views and likes) and word choice (based on automated transcripts of videos) across measles and influenza immunization-related content.

We found some slight differences between different ‘flu’ and ‘measles’ videos, but found some other interesting things as well. For example, there is a spike in the volume and ‘likeability’ of measles content around the time that measles outbreaks occur.

We also found that while anti-immunization videos use the language of science, they contain slight differences that may make them easy to detect for surveillance systems. This could be useful for detecting trends in anti-immunization content in social media.