Category Archives: Research

Bicycle helmets

Do they matter?

The answer is an overwhelming yes.

Here are just a few numbers from a meta-analysis (i.e., a summary of all existing quantitative research) by Oliver & Creighton (2017) assessing the effectiveness of bicycle helmets in crashes and falls:

51% less likely to experience a head injury
69% less likely to experience a serious head injury
33% less likely to experience a facial injury
And 65% less likely to experience a fatal injury

To boot, other meta-analyses find relatively similar results (Attewell et al., 2001; Elvik, 2011; Høye, 2018).

So yes, bicycle helmets matter.

But recent innovations in bicycle helmet tech have improved their effectiveness a considerable amount.

Here I’m talking about WAVECEL and MIPS (Multi-Directional Impact Protection System).

While these two helmet technologies work in slightly different ways, they essentially soften the impact on the head by separating the helmet and your head from the initial shock.

With a traditional helmet, there is essentially a plastic and foam barrier between your head and what it hits, but your head rotates with the helmet at the same speed (and it’s this initial rotation and acceleration that leads to most head injuries, such as concussions and traumatic brain injuries).

With MIPS and WAVECEL, there is within the helmet a moving liner or collapsible structure, respectively, that decreases this rotation, and ultimately the chance of head injuries (Bliven et al., 2019).

So if you’re in the market for a helmet, I would highly recommend looking out for either MIPS or WAVECEL, with MIPS helmets tending to come in at slightly lower costs because the tech has been around for quite a bit longer.

If you’d like more information about bicycle helmet testing, check out the website for Virginia Tech’s helmet testing lab. They run comprehensive third-party testing on helmets for various sports, including cycling.


Attewell, R. G., Glase, K., & McFadden, M. (2001). Bicycle helmet efficacy: a meta-analysis. Accident Analysis & Prevention33(3), 345-352.Chicago

Bliven, E., Rouhier, A., Tsai, S., Willinger, R., Bourdet, N., Deck, C., … & Bottlang, M. (2019). Evaluation of a novel bicycle helmet concept in oblique impact testing. Accident Analysis & Prevention124, 58-65.

Elvik, R. (2011). Publication bias and time-trend bias in meta-analysis of bicycle helmet efficacy: a re-analysis of Attewell, Glase and McFadden, 2001. Accident Analysis & Prevention43(3), 1245-1251.

Høye, A. (2018). Bicycle helmets–To wear or not to wear? A meta-analyses of the effects of bicycle helmets on injuries. Accident Analysis & Prevention117, 85-97.

Olivier, J., & Creighton, P. (2017). Bicycle injuries and helmet use: a systematic review and meta-analysis. International Journal of Epidemiology46(1), 278-292.Chicago

Project WIMH: Post #5

To what extent could mental health explain the underreporting of work injuries?

A study by Zadow and colleagues (2017) examined whether emotional exhaustion, a core aspect of burnout and a common sign of mental health problems, predicted both reported and unreported injuries among hospital personnel.

They found that reported injuries were not statistically related to emotional exhaustion but unreported injuries were – and the difference between the correlational effect sizes (size of the standardized statistical relationship between injuries and emotional exhaustion) was fairly large (.11 to .30).

Too spent to go through the rigmarole of reporting injuries? Quite possibly.


Zadow, A. J., Dollard, M. F., McLinton, S. S., Lawrence, P., & Tuckey, M. R. (2017). Psychosocial safety climate, emotional exhaustion, and work injuries in healthcare workplaces. Stress Health. doi:10.1002/smi.2740

Project WIMH: Post #4

Almost done vetting the large folder of articles I pulled from the databases!

Came across an interesting paper by Simo Salminen and colleagues (2014) about whether stress captured by a single item (“Stress refers to a situation where a person feels tense, restless, nervous, or anxious, or is unable to sleep at night because his/her mind is troubled all the time. Do you feel that kind of stress these days?” p. 2) was associated with the risk of severe injury 8 years later.

Considering the paper was published, you can bet it does!

In fact, they found that individuals who rated their stress as high compared to those who rated it as low were roughly 42% more likely to experience a severe injury at the 8-year follow-up.

Oh, and this finding also controlled for age, gender, marital status, occupational status, education, and physical work environment.

However, greater clarity was gained when they broke down the overall sample by gender and occupation. Turns out that the association of this stress item with later severe injuries was only significant within males and individuals in blue-collar occupations (i.e., high stressed blue-collar males were more likely to experience a severe injury than their low stressed blue-collar male counterparts).

Goes to show that the bigger picture findings can sometimes mask what’s actually happening.


Salminen, S., Kouvonen, A., Koskinen, A., Joensuu, M., & Väänänen, A. (2014). Is a single item stress measure independently associated with subsequent severe injury: A prospective cohort study of 16,385 forest industry employees. BMC Public Health, 14(543), 1-7. 

Project WIHM: Post #3

The persistence of post-traumatic stress symptoms following an injury is pernicious.

Haagsma and colleagues (2010) followed up with a general population of patients 2 years after treatment for an injury.

Post-traumatic stress symptoms among these patients were negatively associated with almost all the functional and health-related quality of life measures in the study (e.g., problems with mobility, emotion, cognition, as well as considerably higher levels of pain, discomfort, anxiety & depression).

One take away from this study is the emphasis surrounding the treatment of physical AND psychological symptoms following an injury. If the psychological aspects of traumatic injuries are not rehabilitated in tandum with the physical aspects of injuries, there could be serious long-term consequences towards functioning and quality of life.

This is said in light of the study design limitations. Most importantly, the study does not allow one to be conclusive about the direction of the relationship between PTSD symptoms with functional and health-related quality of life (i.e., do PTSD symptoms lead to worse functioning/quality of life, the opposite, or is something else leading to both?). However, it does allow one to infer that individuals who continue to exhibit PTSD symptoms 2-years after an injury are far more likely to suffer from an overall lower quality of life.


Haagsma, J. A., Polinder, S., Olff, M., Toet, H., Bonsel, G. J., & van Beeck, E. F. (2012). Posttraumatic stress symptoms and health-related quality of life: A two year follow up study of injury treated at the emergency department. BMC Psychiatry, 12(1), 1-8. 

Project WIMH: Post #2

The article vetting process continues.

It can be hard to read through some of the research on this topic. Here is a quote from a qualitative study by Cacciarro & Kirsh (2006) on the mental health needs of injured workers:

“It’s just a domino effect. It’s affecting my children. My kids come home from school and I haven’t got dinner made because I haven’t got the energy to make it. And they’re, we want mom back. We want our old mom back.”


Nevermind the lack of compassion that injured workers often feel when dealing with compensation systems, the alienation and stigma surrounding injuries, and having to come to terms with temporary or permanent unemployment.

That aside, my supervisor and I (along with several other colleagues) have started to look at these indirect or vicarious effects of work injuries on the mental health of teenagers and some preliminary findings suggest that living with an injured parent has a bigger detrimental impact on mental health than do injuries experienced directly by young workers. An area of research that I suspect will get increasing attention in the coming years.


Cacciacarro, L., & Kirsh, B. (2006). Exploring the mental health needs of injured workers. Candian Journal of Occupational Therapy, 73(3), 178-187.

Project WIMH: Post #1

Back at it again. It’s been a while since I’ve had an opportunity to move this project forward on the empirical side.

To help with this process, I’ve decided to begin blogging my efforts towards completing Project Work Injury and Mental Health (WIMH).

Over the last semester I finally wrapped up the database search, which consisted of a ludicrous amount of screening (~23,000 articles!).

I also had the great opportunity to present some of the preliminary findings at SIOP 2019 in a symposium on mental health at the workplace. I’m very grateful to Dr. Jennifer Dimoff and her PhD student, Stefanie Fox, for organizing the symposium.

Now that I’ve screened all the articles from the database search, it’s time to vet through the articles I pulled. Usually you have to be pretty intellectually ruthless with this process, but sometimes you can’t help spending too much time on interesting articles.

For instance…

…Betters (2010) found that individuals who were injured at work were more likely to gain weight if they thought they would benefit from mental health services (albeit, no effect size was provided), hinting that the pressure to reduce the discprepancy between where they are physically with where they want to be is having psychological consequences.

…Blake and colleagues (2014) found that over close to 50% of individuals who witness work-related fatalities experience probable or sub-threshold PTSD symptoms, which in turn have striking effects on depression, life functioning, and well-being. This research highlights the importance of psychological interventions for dealing with traumatic events at work.

Anyways, back to being ruthless for a bit as I vet through the pulled articles!


Betters, C. J. (2010). Weight gain and work comp: A growing problem in the workers’ compensation rehabilitation system. Work, 37(1), 23-27. doi:10.3233/WOR-2010-1053

Blake, R. A., Lating, J. M., Sherman, M. F., & Kirkhart, M. W. (2014). Probable PTSD and Impairment in Witnesses of Work-Related Fatalities. Journal of Loss and Trauma, 19(2), 189-195. doi:10.1080/15325024.2013.775889

Personality and Safety: A Review of Beus, Dhanani, & McCord (2015)

Are there certain features of our personality that increase or decrease the likelihood that we will behave safely or be involved in accidents at work? A number of recent meta-analyses have, with increasing rigor, attempted to combine all we know about the relationship between our Big Five personality characteristics (i.e., Openness to experience, Conscientiousness, Extraversion, Agreeableness, and Neuroticism – think OCEAN) and safety at work (Clarke & Robertson, 2005; Chrisitan et al., 2009; Beus et al., 2015). So, what can we say about this relationship?

First, it exists! There is indeed a relationship between four of the Big Five personality characteristics and safety. Surprisingly, agreeableness has consistently shown itself to be the largest and most robust predictor of safe behaviour. I say surprisingly because I would have guessed that conscientiousness, how orderly and responsible we are, would have shown the strongest relationship. Yet, conscientiousness came a modest second place (similar effect size but less variance explained) in terms of predicting safe behaviour. Finally, extraversion and neuroticism showed much smaller but consequential relationships with workplace safety behaviour, such that the more extraverted and neurotic individuals are, the more likely they are to behave unsafely at work.

The idea that agreeableness is the most robust predictor of unsafe behaviour is fascinating and has many implications. Beus and colleagues discuss many of these implications in their paper and I tend to agree with the idea that agreeableness motivates people to seek communion. Essentially, the goal of communion is to seek meaningful and healthy relationships with others. People are thus less likely to behave unsafely to avoid putting others at risk or to make the group suffer because of their own carelessness. In turn, this finding has tremendous implications for the power of social interventions and social features of the organization for shaping safe behaviour. Reframing safety performance as prosocial and adding information about how behaviour affects others to feedback systems are examples of how organizations can improve safety by activating the motivation towards communion.

While I find the idea that agreeableness is the best personality predictor, I could imagine there are almost certainly boundary conditions to this finding. For instance, I could imagine that an agreeable person who finds him or herself in a group that behaves poorly and unsafely will likely be swayed by the group to also behave in a poor and unsafe manner. I cannot think of any empirical evidence off the top of my mind to support this idea, but it would be a fascinating study and one that is entirely possible to do given the advances in multilevel analyses.

Moving on, it came as no surprise that conscientiousness was important to workplace safety behaviour. What was interesting was the idea that extraversion and neuroticism were related to unsafe work behaviour. Beus and colleagues examined particular features of these broad personality characteristics to provide insight into what is driving these relationships. What they found was that the relationship between extraversion and unsafe behaviour was largely driven by a feature of extraversion called sensation seeking; thrill seekers put themselves into more risky situations on average. Meanwhile, the features of neuroticism that were driving the relationship are anger and impulsiveness, while anxiety actually reduced unsafe behaviour. You could imagine the overlap between sensation seeking and impulsiveness to be a particularly dangerous combination of personality when it comes to safety.

While personality and workplace safety behaviour were shown to be are related, what about personality with accidents and injuries? Beus and colleagues address this question both theoretically and empirically. They proposed that personality would be related to accidents and injuries through unsafe behaviour. That is, behaviour would fully mediate or explain the relationship between personality and accidents and injuries. This is what they found*. If you want to understand how personality is related to accidents and injuries, you need to understand how personality drives workplace safety behaviour.

The role of personality on workplace safety behaviour and safety outcomes has become more clear through these reviews. However, there could still be doubt that personality is rendered unimportant when compared to other predictors of workplace safety. For instance, does personality still matter when compared to a robust predictor of workplace safety such safety climate (i.e., the collective perceptions of an organization’s safety practices, policies, and procedures). Again, Beus and colleagues rose to the occasion to provide an answer. In their meta-analysis they showed that personality still mattered when taking safety climate into account (although slightly less than in isolation).

Based on the reviews, especially that completed by Beus and colleagues, we can be confident in a number of things. First, we know what the most important personality characteristics are in predicting workplace safety behaviour and their relative magnitude. Second, we can confident that personality is indirectly related to accidents and injuries through safety behaviour. Finally, we can be sure that personality can explain safety behaviour when taking other predictors, particularly safety climate, into considering.


*NOTE. Well not exactly. Results from Beus et al (2015) suggest that a partially mediated model has a slightly better statistical fit. However, Beus and colleagues suggest that this is only because of how certain personality characteristics are measured, such that some measures are behavioural in nature. Given that the statistical techniques used were not designed to detect and account for methodological contamination, researchers need to make judgement calls as Beus and colleagues did – and to their credit, argued that a fully rather than partially mediated model is appropriate.


Beus, J. M., Dhanani, L. Y., & McCord, M. A. (2015). A meta-analysis of personality and workplace safety: Addressing unanswered questions. Journal of Applied Psychology100(2), 481-498.

Clarke, S., & Robertson, I. (2005). A meta‐analytic review of the Big Five personality factors and accident involvement in occupational and non‐occupational settings. Journal of Occupational and Organizational Psychology78(3), 355-376.

Christian, M. S., Bradley, J. C., Wallace, J. C., & Burke, M. J. (2009). Workplace safety: a meta-analysis of the roles of person and situation factors. Journal of Applied Psychology94(5), 1103-1127.