Annunciators Make Ineffective Performance Indicators
03.06.96 21:54 Filed in: Performance
Indicators
Annunciators make poor performance indicators
because they are driven by events rather than
being used to drive performance. From a human
factors perspective, annunciators exist to
compensate for our inability to monitor large
amounts of changing data effectively all the
time. Thus, an annunciator is provided to warn
the operator when a parameter exceeds some
boundary. Note that the annunciator has limited
value once in the alarm state because it cannot
tell you anything else about the situation other
than its still in the alarm state.
Annunciators thus do not offer the feedback mechanisms typical of numeric type indicators such as information on rate or future state. In general the annunciators lack a linkage to analog interpretations that human beings use. Annunciators lack scale , trend or rate information. They have no ability to display current progress versus the goal.
Annunciators are not anticipatory devices. They exist in one state or another. The use of three state annunciator windows (OK, Caution, Alarm) further confuses the purpose of annunciators regarding state change. The change in state is not necessarily proportional to the deviation from plan. Thus you can be in an alarm state for a minor deviation as well as a major deviation. It is the old teaspoon of sewage in the barrel of wine problem, its still sewage.
Annunciators change state and then provoke action when what is desired is continuous action to achieve the goals. Continuous action is monitored with indicators that continuously display the value and if possible trend.
Annunciators lack predictive power. There is no inference based upon current state to future states
The coloration of annunciator windows changes with the state of the window. Unfortunately, there is no causal linkage generated from color change to what action might be required to reverse the state change. Thus the use of color coding for state change lacks a feedback mechanism to point towards action required or desired.
The key to distinguishing effective indicating devices is the concept of DRIVING versus DRIVEN. Indicators associated with changing the current state of the process or business would be characterized as DRIVING indicators in a sense analogous to the speedometer on a car in which the operator varies the pressure on the gas pedal to adjust speed as indicated by the speedometer. Indicators that reflect what has just been accomplished e.g. historical items would be characterized as DRIVEN indicators. In the car analogy the odometer is a DRIVEN indicator because it reflects what has just happen as well as what happened before. Useful as the odometer may be to selling a used car, it does not have much relevance to the act of driving the car. In essence the odometer is a bean count of the miles a car has traveled.
Reference cited: McCormick, Ernest J., Human Factors in Engineering and Design,(New York: McGraw-Hill, 1982
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This article and incorporated images are ©1996 J. M. O'Connell All Rights Reserved. Permission is granted for reproduction not for profit in its entirety including this copyright notice.
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Annunciators thus do not offer the feedback mechanisms typical of numeric type indicators such as information on rate or future state. In general the annunciators lack a linkage to analog interpretations that human beings use. Annunciators lack scale , trend or rate information. They have no ability to display current progress versus the goal.
Annunciators are not anticipatory devices. They exist in one state or another. The use of three state annunciator windows (OK, Caution, Alarm) further confuses the purpose of annunciators regarding state change. The change in state is not necessarily proportional to the deviation from plan. Thus you can be in an alarm state for a minor deviation as well as a major deviation. It is the old teaspoon of sewage in the barrel of wine problem, its still sewage.
Annunciators change state and then provoke action when what is desired is continuous action to achieve the goals. Continuous action is monitored with indicators that continuously display the value and if possible trend.
Annunciators lack predictive power. There is no inference based upon current state to future states
The coloration of annunciator windows changes with the state of the window. Unfortunately, there is no causal linkage generated from color change to what action might be required to reverse the state change. Thus the use of color coding for state change lacks a feedback mechanism to point towards action required or desired.
The key to distinguishing effective indicating devices is the concept of DRIVING versus DRIVEN. Indicators associated with changing the current state of the process or business would be characterized as DRIVING indicators in a sense analogous to the speedometer on a car in which the operator varies the pressure on the gas pedal to adjust speed as indicated by the speedometer. Indicators that reflect what has just been accomplished e.g. historical items would be characterized as DRIVEN indicators. In the car analogy the odometer is a DRIVEN indicator because it reflects what has just happen as well as what happened before. Useful as the odometer may be to selling a used car, it does not have much relevance to the act of driving the car. In essence the odometer is a bean count of the miles a car has traveled.
Reference cited: McCormick, Ernest J., Human Factors in Engineering and Design,(New York: McGraw-Hill, 1982
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This article and incorporated images are ©1996 J. M. O'Connell All Rights Reserved. Permission is granted for reproduction not for profit in its entirety including this copyright notice.
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