From Proceedings of the Human Factors and Ergonomics Society 42nd Annual Meeting, October 5-9, 1998.
QUANTIFYING OFFICE PRODUCTIVITY: AN ERGONOMIC FRAMEWORK
Alan Hedge
ABSTRACT
An ergonomic framework for conceptualizing and measuring office is described.
This framework is based on the analysis of task time, posture and sequence, and
the subsequent the determination of the most appropriate pace, posture, and
activities for any office job. The framework assesses various measures of pace,
proficiency, and posture that currently can be readily assessed by ergonomists,
and it uses these measures to quantify the short- term duty cycle productivity
(pop! and in the longer-term life- cycle productivity (LCP) of office workers.
The approach that will be described allows companies to evaluate the impact of
ergonomic interventions on the productivity of their workers. The benefits of
this ergonomic approach to assessing productivity are discussed.
INTRODUCTION: THE PIONEERS OF PRODUCTIVITY
"In order to improve productivity, the manager must first be able to measure
it." (Riccio, 1976, p. 97).
At the start of the 20th century, Frederick Taylor, Frank Gilbreth and Henry Ford radically changed American industrial thinking about ways to organize work, and optimize productivity.
Frederick Taylor developed the scientific management approach to analyzing work activities. This approach involved observing workers and timing the performance of each task (Aft, 1992). Frank Gilbreth pioneered "Motion Study" as a method for increasing the efficiency of workers that was an integral component of Taylor's Scientific Management approach. He argued that Motion Study increases output by "selecting and teaching each workman the best known method of performing his work" (Gilbreth, 1911, page 3). Gilbreth's basic approach involved observing how people currently performed their work tasks, enumerating the motions involved and the variables affecting each motion, and then eliminating wasted movements that did not add value to the work and awkward postures that accelerated fatigue of the worker to produce a "best practice" way of performing that work. In his 1911 book, he maintained that:
- "the direction of motion that is most economical is the one that utilizes
gravitation" (p. 74).
- workers should "make the shortest motions possible (p. 79).
- only necessary motions should be made (p. 81). "each motion should be made so as to be most economically combined with the next motion, like the billiard player who plays for position" (p. 83). "the faster the motions, the more the output" (p. 84).
"The economic value of motion study has been proved by the fact that by means of it workmen's outputs have been more than tripled, production costs lowered, and wages increased simultaneously." (p. 110).
Henry Ford pioneered the assembly line, a change in the organization of the manufacturing process that spearheaded America's dominance of the world's industrial output. Ford believed that optimum productivity was maintained by moving work tasks past the worker at an appropriate pace and by ensuring that all activities added monetary value to the end product, called value-added activities. If an activity didn't add value to a product Ford maintained that it was a wasted activity.
In summary, what Taylor, Gilbreth and Ford did was to systematize the analysis of how long task activities take, what work postures are least fatiguing, and what sequence of task activities is most efficient. Together, the analysis of time, posture and sequence allow the determination of the most appropriate pace, posture, and activities for any job.
Ideas based on this pioneering work are in practice in many industrial settings, but have yet to have a substantial impact on most office, which now are the dominant American workplace. Since the 1960s, the media repeatedly have reported that annual productivity growth in America has declined relative to many other countries (Aft, 1992), and concerns about a lack of growth in office productivity remain.
Part of the problem in interpreting claims about office productivity stem from the diverse measures of productivity that depend upon the disciplinary perspective that is taken. Accountants try to gauge productivity by evaluating the effectiveness and worth of business activities, and a multiplicity of financial ratios are utilized (Norman and Bahiri, 1972). For the economist, productivity is measured by some equation that defines the net output per employee as a function of the annual added value and either the number of employees or their total cost (ibid.). From an engineering perspective, productivity is regarded as synonymous with the efficiency of the producing activity, which is evaluated by comparing outputs and inputs (ibid.). This paper proposes an ergonomic definition of productivity. Although there are many different definitions of productivity, all recognize the role of 3 components: management, capital and labor. For productivity to increase, management must know the existing performance level and have a desire to raise this, capital investment in new technologies too boost output must be made, and labor (workers) must be able perform tasks more effectively. At the root of an ergonomic approach to boosting productivity is the need to improve the efficiency of individual workers, which in turn assumes that a manager has detailed knowledge of worker performance, and that the worker receives this feedback. Unfortunately, in the modern white-collar workplace, many managers do not have such measures for their workers.
PRODUCTIVITY IN OFFICES
After more than 20 years of investing in widespread computerization, the best
economic estimates rate annual white- collar productivity as being flat. Many
have argued that white- collar productivity is immeasurable, because it entails
the production of information, which involves thinking, researching, discussing,
processing information, and because its output is the production of information
not necessarily countable "widgets". It is true that much white-collar work
involves less physically intensive work than that in production industries, but
this doesn't not mean that white-collar productivity cannot be quantified.
However, from an ergonomic standpoint, it should be possible for any
organization to operationally quantify their white-collar productivity. The
greatest efficiencies in American offices can only be realized when productivity
is quantified and used to gauge changes in work processes, practices and
equipment, such as ergonomic furniture. Without quantification, American companies may be losing untold billions of dollars to inefficient
working.
The idea that most white collar workers are processing information and do not produce anything tangible is misleading: office workers process information. Information is a product. In an industrial assembly line an incomplete product passes a worker who applies some value-added process to the product. Similarly, in an office information passes to and between workers either as hard copy, voice (phone) or electronically, and workers must perform value added activities to process this information. For the vast majority of workers, value-added information processing activities equate to activities spent working at a computer. This can be readily quantified by recording input activities, such as keystrokes and input device movements. Additionally, the time spent performing a task and the posture assumed while working, an indicator of injury risk, also can be measured. It is proposed that the collection of such data can provide the foundation for this proposed approach to measuring office productivity.
Life cycle and duty cycle costs
In functional terms, an office worker is an asset to an organization as is a
piece of office equipment, such as a photocopier. The worker performs activities
that are bounded in time and can be defined as a duty cycle, in the same way as
photocopier performance can be analyzed in terms of its duty cycle for making
copies. For a worker the duty cycle involves quantifying the activities and the
recovery time over a suitable cycle period. For convenience, and because wages
are based on hourly rates, in this paper the duty cycle for an office worker
will be defined as a one-hour unit of time.
Duty cycle data can be used to compute the life-cycle costs for a photocopier. Similarly, life cycle costs can be estimated for an office worker, who also performs many duty cycles over the course of their working life. Just as a copier can break down if it does not receive scheduled maintenance, so a worker can become injured and even disabled if not properly 'maintained' by an appropriate work schedule, training and equipment. Thus, an ergonomic measures of office productivity can be expressed in the short term by quantifying duty cycle productivity (DCP) and in the longer-term by quantifying life-cycle productivity (LCP). In human terms, LCP also includes the lost work attributable to injuries and premature retirement from the workforce.
A COMPONENT MODEL OF OFFICE PRODUCTIVITY - the 3P's.
The basis of all quantifiable office work involves measuring 3 components,
proficiency, pace, and posture. Each of these 3 components involves the
following measurements:
Proficiency - for a computer worker most activities involve using a keyboard and/or input device. Such activities can be recorded automatically and analyzed as: value-added work (e.g. correct keystrokes or mouse movements) wasted work (e.g. making errors, correcting errors)
Pace - for a computer worker the amount of time spent using a keyboard and/or input device (e.g. mouse, touchpad, etc.) can be recorded automatically. However, chronological time alone is not a good indicator of performance because workers must learn to work at an appropriate pace so that they can sustain work output throughout the work day, just as a marathon runner needs to learn how to run at a certain pace to be able to endure a 26 mile run. Appropriate pace combines both work and rest periods. Even office equipment requires some recovery time. Consequently, pace can be analyzed as:
appropriate value-added time on task the amount of time spent performing value-added work plus the appropriate rest breaks/recovery time required to sustain performance.Wasted time - time spent doing nonvalue added activities and/or a penalty for work performed at an inappropriate pace (e.g. ignoring appropriate rest pauses).
Posture - this describes how a worker is doing his/her work. Posture can be quantified as:
low risk postures - the optimal postures for performing activities throughout the duty cycle. Low risk postures pose the minimal level of injury risk to workers.
high risk postures - these are all of the suboptimal postures workers might use to perform activities throughout the duty cycle. The more deviated the work posture the greater the risk of injury. Prolonged work in high risk postures adversely affects duty cycle productivity by slowing performance, but poor posture has the greatest impact on life-cycle productivity, ultimately causing worker injuries and disabilities.
Posture is directly affected by the type of office equipment provided to the worker, especially the location of the keyboard, mouse and monitor, in the same way that a runner's gait would have to change if s/he had to run in snow shoes rather than sneakers.
QUANTIFYING THE 3 COMPONENTS OF OFFICE PRODUCTIVITY
Proficiency, pace and posture can be quantified and combined into a simple
additive model that assesses both duty cycle productivity and life-cycle
productivity as follows:
1. Quantifying Proficiency
Two sets of activities can be defined for any unit of computer- based work, and
automatically recorded by software as: Value added actions (VAA) - these include
correct keystrokes and appropriate mouse clicks per hour. Wasted actions (WA) -
these include incorrect keystrokes, error correcting keystrokes and incorrect
mouse clicks per hour.
These measures can be used to define an effective activity (EA) calculated for each duty cycle. The EA varies between 100% (perfect performance) and 0%. The higher the value of the EA the greater the proportion of value-added work being done. Thus,
EA = (VAA/(VAA+WA))* 100)
2. Quantifying Pace
An appropriate pace can be defined for any job as being that combination of
value-added work time and the required rest/ recovery time that allows the
worker to sustain performance at an acceptable level. This involves measuring
two sets of variables: time and scheduled rest breaks. Pace can be automatically
recorded by software as:
Value added time (VAT) - the time in a duty cycle spent performing value added actions plus the time spent taking the appropriate scheduled rest breaks. Wasted time (WT) - the time in a duty cycle spent performing wasted actions plus the time spent skipping the appropriate scheduled rest breaks.
These measures can be used to define an average hourly effective time (ET) that varies between 100% (perfect performance) and 0%. Thus,
ET = (VAT/(VAT+WT)* 100
Effective performance
The percentage effective performance (EP) for the duty cycle can now be computed
from the effective activity and the effective time measures as follows: EP = (EA
+ ET)/2
Life cycle issues
Life cycle issues arise when workers' skip scheduled rest breaks, because this
increases the risk of a cumulative trauma injury. Hence, in the life-cycle
equation a correction factor has to be applied for this as follows:
Target breaks (TB) - the number of scheduled rest breaks in a duty cycle (set by a company).
Skipped breaks (SB) - the number of scheduled rest breaks skipped in a duty cycle.
These measures can be used to define a utilization factor (UF) that varies between 100% (perfect utilization of rest breaks) and 0% (no breaks). Thus,
UF = ((TB-SB)/TB)* 100
Together, the ET and UF can be used to determine an average pace factor (PF) for each duty cycle that varies between 100% (perfect pace) and 0%. Thus, the pace factor can be calculated as follows:
PF = (ET+UF)/2
Performance Trade-offs
A worker might have to achieve a performance target by skipping recommended rest
breaks and this can be tracked by an index that measures this, called
performance tradeoff (PT), which can be calculated as follows:
PT= (EP*UF)/100
The performance trade-off varies between 100% (no trade-offs, no skipping breaks, 100% adherence to schedule) and 0% (skipping all breaks, no adherence to preset work schedule).
3. Quantifying Posture
An appropriate posture can be defined for any job. Posture can be readily
recorded by using a posture targeting method, such as RULA (McAtamney and
Corlett, 1993). Posture targeting allows measures of:
Ideal posture (IP) - the desired posture score for the duty activities expressed as a RULA score (normally a value of 2 for office work).
Observed posture (OP) - the actual posture score observed for the duty activities expressed as a RULA score.
Posture (RULA) scores are measured intermittently for a job but posture has a substantial effect on life-cycle productivity. Posture measures can be used to define a body posture factor (BPF) that varies between 100% (perfect posture) and 0%. Thus,
BPF = (IP/OP)*100
4. Life cycle productivity
The percentage life cycle productivity (LCP) can now be computed from the
information collected for the duty cycle and for the work posture as follows:
LCP = (EP * BPF)/100
Finally, the injury risk can be expressed as a relative risk as follows:
Injury risk = 100/LCP
CONCLUSIONS
An ergonomic framework for quantifying computer-based office work has been
described. Future work should test the validity of the various measures that
have been proposed and also test how well this approach can be used to analyze
office work and evaluate the effects of ergonomic interventions.
REFERENCES
Aft, L.S. (1992) Productivity, measurement and improvement. 2nd ed. Englewood
Cliffs, NJ, Prentice-Hall.
Gilbreth, F.B. (1911) Motion Study: A method for increasing the efficiency of the workman. New York, D. Van Nostrand Company.
McAtamney, L. & Corlett, E. N. (1993). RULA: A survey method for the investigation of work-related upper limb disorders, Applied Ergonomics, 24 (2), pages 91-99.
Norman, R.G. and Bahiri, S. (1972) Productivity measurement and incentives. London, Butterworths.
Copyright © 1998 by Human Factors and Ergonomics Society. All rights reserved. For a complete copy (with tables and figures), contact Lois Smith at hfes@compuserve.com.