Further Confusion on the Task Analysis Front

by Ian Chong, CPE

As a professional ergonomist/consultant, I am frequently asked what really is a "task analysis"? In the premier issue of Workplace Ergonomics, (Oct 84), we defined differences between the classic terms "Job Analysis" and "Task Analysis". However further clarification of the term "Task Analysis" appears prudent.

In the world of professional ergonomics, there are two types of task analysis: qualitative and quantitative. Both are legitimate forms, but which one will your ergonomist use—and why?

If your ergonomist displays his goniometers, clipboards full of statistics, video cameras, and a large TV with fast forward and slow motion, you are probably in the market for a large scale training approach to rudimentary issues and a so-called ergonomics program. However, most organizations don't need an ergonomics program, they need safer, more productive workplaces. With this quantitative approach, you also should be prepared to implement many of the principles, practices and training yourself with guidance from the quantitative ergonomist.

Beyond these quantitative instruments, however, is a tool that is perhaps the most important of all, it's also the tool that many ergonomists don't have in the bag they bring to your workplace: Creativity.

If you are looking for specific help in addressing significant identifiable and prominent biomechanical/occupational injuries such as repetitive motion, strains, sprains, disk rupture, neural impingement muscle tension, or other musculo-skeletal problems you will need an ergonomist who includes in his/her toolbox command of this elusive creativity skill and who also understands a qualitative or holistic approach.

This type of ergonomist understands the necessity for anatomical, analytical and creative solution (read design) approach. This type of ergonomist considers pure physiology, medical anatomy and engineering in the redesign of workstations, tasks, methods, processes, tools and equipment.

The Quantitative Task Analysis

The Quantitative Task Analysis specifically documents things like, range of motion, task frequency, and force magnitude. It also correlates biomechanical breakdown or injury potential to empirical data. Quantitative analyses are often associated with academic or evaluation purposes. They are a means to say why an injury exists and focuses specifically on how the biomechanical breakdown can occur. They are performed by video, photography or observation. Specific worker motions are recorded and reviewed with frequency, duration and magnitude being the general statistics gathered and correlated into logical conclusion.

For instance a quantitative task analysis will determine how many times a warehouse worker bends over and lifts a six gallon pack of spring water and moves it from the back of a truck to a forklift. Or it will show how many times a customer service representative reaches over, extends the arm, uses a pinch grip and flexes the wrist in obtaining the company phone book. It will also document these statistics within a unit time such as hour, minute and second, compare this data to published standards, concluding that if your warehousers lift this much weight with this frequency in this much time, you have this much probability of back strain, sprain, pain or injury such as disk rupture. Therefore you need to alert your workers as to how and how much they should lift. The analysis will also help guide the appropriate training so you can impart this important information to your workers.

This quantitative approach is especially effective in establishing a proactive program to make people aware of what to do in preventing injury for the long term. However, the greatest deficiency of quantitative approach is its inability to determine how to specifically fix the problem in hard terms such as task, equipment, method or process modifications. It falls short in helping the worker who is in severe pain right now, under medical care and can't work or at least can't work up to capacity, either to the workers satisfaction or to the organizations need. These workers (and their organization) need help yesterday!

The Qualitative Analysis to the Rescue

This methodology's strength lies in situations where an injury results from an identified task(s). It provides solutions based on a solid understanding of biomechanics, anatomy, anthropometry, kinesiology and design. The qualitative ergonomist, acting like Sherlock Holmes, identifies which specific anatomical tasks(s) postures or positions, (often reflective of tools, equipment or environment), have a causal relationship to the injury. Qualitative ergonomists use this biomechanical task analysis to design or redesign offending tasks, positions, postures, methods, processes, equipment or environments.

For instance if you own a bank and your proof operators are operating poofing machine, flipping 1200 checks per hour and developing severe crippling tendonitis, you need a qualitative ergonomist who understands the mechanism of injury and who can design check stackers to remove the painful motions. Or you may own a chicken plant and workers on your chicken line are developing disabling carpal tunnel syndrome pulling gizzards out, directly affecting your quality control. A qualitative ergonomist can analyze your tasks and develop a specialized tool to remove gizzards faster and more efficiently, keeping quality and productivity standards up and most of all eliminating debilitating hand/wrist abuse.

You might have also supplied your entire keyboard operator group with state-of-the-art chairs, articulating keyboard trays, pointing devices, monitor elevators, ergonomics training, and still painful backs, shoulders, elbows, wrists, hands and fingers abound. What do you do? Wasn't all that equipment and training supposed to be ergonomic?

The missing link is the qualitative analysis that determines exactly what the mechanism of injury source is within all that fancy new ergonomic equipment A qualitative analysis will show you how your keyboarders are not adjusting the armrests correctly and are inadvertently positioning themselves so they have impacted a combination of cubital tunnel irritation, causing severe elbow pain and shoulder tension which compresses shoulder and arm nerves resulting in pain, numbness and tingling. Specifically addressing armrest issues for the workers will alleviate this problem.

Inclusion of workstation correction appears to be the key in distinguishing between quantitative and qualitative task analysis. Both techniques are valuable tools. Both will ultimately help injured workers and both provide significant research and principles. However, qualitative studies are in many cases more adept at providing an immediate design solution, while quantitative techniques appear to be most applicable when the impact of task performance is unknown and you want to determine how ergonomic issues affect your organization. Both types are needed and valuable, but it is an understanding of each technique's limitations that insures the most effective approach is applied.

 

Ian Chong, CPE is Principal of Ergonomics Inc. in Seattle WA. USA. The firm has over 20 years of experiences providing ergonomic solutions to both public and private sector companies. For more information please contact:

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