Why I love quantification

Introduction

I came to Human Factors from a psychology background and the concept of quantifying human behaviour to predict the likelihood of errors seemed unrealistic to me.  Despite the patterns of behaviour that psychologists have identified over the years, I was convinced that there were too many variables, too many confounding factors, too many individual differences to put a number on it.

Human Factors and Quantification

So, what changed?  Well, in the late 90’s, I started working with Jerry Williams the originator of HEART (Human Error Assessment and Reduction Technique, 1985).  When he explained the work behind the technique, and how that data showed that predictable, repeatable results could be calculated to a sensible approximation, I was hooked.  It seemed obvious to me that quantification was the way to go – it opened an understanding of Human Factors to non-specialists and told engineers why Human Factors was important. 

No longer did I have to assert it was important to provide feedback to a user of equipment, now I could say a user could be four times more likely to make an error if they didn’t have feedback.  I could show that a task could be doomed to be unreliable, simply because of the nature of that task. 

I was excited. 

It’s much more powerful to put a number to the influences on performance when we’re persuading others to invest in design, to introduce safety measures, to employ more staff, to change their workload, to provide support and to change the tasks we give to people etc., etc., etc. 

Of course, I soon hit the wall of “whatabouters” and “no, no, no, people and systems are more complex than this”, which morphed into, “ah, but these data are so old”.  Then there’s the manipulators of the data to meet their own ends, there are those that want absolutes, those that want certainty, and those that want every eventuality covered in their analysis. 

All these criticisms and concerns haven’t diminished my enthusiasm for HEART; they are levelled at every quantification risk assessment method not just in human reliability.   And yet such tools, can be incredibly powerful in understanding, communicating, and managing risk.  I’m on a mission to share the benefits of quantification with the world!