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Happy New Year from the team at Optimal Performance Consultants to all of our clients and readers.
To get 2014 started the Ergonomic Team at OPC Inc would like to highlight the fact that people mix up correlation with causation. We argue based on the article below from Reuters that these assumptions cost employers in Canada far too much in Compensation payments and LTI.  Time to force the boards to stick to excellence in the science of cause and effect is what we argue for.
We have worked for years with clients to help them show the WCB’s in Canada that most jobs are NOT the cause of an MSI. This is an expensive correlational error for the boards to make on behalf of employers. Read more about this in the article below and start to make sure the boards understand most MSI’s are NOT caused by the workplace solely. ¬†Signed the Ergonomic Team at OPC Inc
Josh Fick, Alex Hardie, Jacob Thadickal, Kerry Vergeer and Rachel Bredin.

The classic example of¬†correlation¬†not equaling causation can be found with¬†ice cream¬†and — murder. That is, the rates of¬†violent crime¬†and murder have been known to jump when ice cream sales do. But, presumably, buying ice cream doesn’t turn you into a killer (unless they’re out of your favorite kind?).

© Carlo Allegri/Reuters/Corbis

You would think by now that we could say unequivocally what causes what. But the question of cause, which has haunted science and philosophy from their earliest days, still dogs our heels for numerous reasons. Humans are evolutionarily predisposed to see patterns and psychologically inclined to gather information that supports pre-existing views, a trait known as confirmation bias. We confuse coincidence with correlation and correlation with causality.

For A to cause B, we tend to say that, at a minimum, A must precede B, the two must covary (vary together), and no competing explanation can better explain the covariance of A and B. Taken alone, however, these three requirements cannot prove cause; they are, as philosophers say, necessary but not sufficient. In any case, not everyone agrees with them.

Speaking¬†of philosophers,¬†David Hume¬†argued that causation doesn’t exist in any provable sense. Karl Popper and the Falsificationists maintained that we cannot prove a relationship, only disprove it, which explains why¬†statistical analyses¬†do not try to prove a correlation; instead, they pull a double negative and disprove that the data are uncorrelated, a process known as¬†rejecting the null hypothesis.

With such considerations in mind, scientists ( and the decision makers at the WCB’s in Canada according to OPC) must carefully design and control their¬†experiments¬†to weed out bias, circular reasoning, self-fulfilling prophecies and hidden variables. They must respect the requirements and limitations of the methods used, draw from¬†representative samples¬†where possible, and not overstate their results.

Tell us what you think about this Blog, article and our arguments on this topic via @OPCergo or our Blog below.

  • Jamila Mohideen

    How many employers in Canada passively let the WCB’s in each province determine if there is a cause & effect relationship between & injury & the job demands? In our experience most employers never seem to try to counter this very flawed decision-making process which takes place every day in Canada. Optimal Performance recommends employers do two new things in DM & Ergonomics for 2014 to save costs; 1. Make sure you have up to date Job Demands Analysis for each & every job in your workplace including mental & environment demands & 2. submit the JDA’s to the WCB in your province when adjudication is occurring & request that the science of cause & effect relationships be used every time.

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