The words "continual" and "continuous" are often used interchangeably. But, when either is placed in front of the word "improvement" and used to describe the expectations of your management system, it’s important to know the difference and understand the requirements involved with each.
To get a better understanding of what this means to your organization, we posed the following question to quality management system (QMS) and environmental management system (EMS) experts, as well as members of the International Organization for Standardization’s (ISO) U.S. Technical Advisory Groups (TAG) responsible for the development of the QMS and EMS standards: Is there a difference between continual and continuous, and what does it mean to either a QMS or EMS?
The first thing to note is that both words appear among the QMS and EMS standards. Lloyd D. Brumfield, quality assurance engineering specialist for MSX International/Ford Customer Service Division and member of The Informed Outlook editorial advisory board, made a few observations:
"The QS-9000 first, second and third editions use the word continuous numerous times but never use the word continual. The ISO standard uses the word continual, but never continuous. The words continual, continuous improvement and continuing suitability are found in ISO 9001:1994, ISO 9002:1994, ISO 9003:1994, ISO 14001:1996 (Figure 1 system model, 3.1 and 4.2.b) and 4.1.3 of the Society for Automotive Engineering’s AS 9000:1997.
"The ISO 14001:1996 definition of continual improvement says it is the ‘process of enhancing the EMS to achieve improvements in overall environmental performance in line with the organization’s environmental policy.’ A note states, ‘The process need not take place in all areas of activity simultaneously.’"
So, what do experts in quality and environmental management have to say about the appearance of the words, and how should they be interpreted?
Why did the developers of ISO 14001 use continual rather than continuous to describe the expected rate of improvement for an EMS? According to Suzan Jackson, business manager of environmental services for Excel Partnership Inc. and an EMS consultant, "The authors of the ISO 14001 standard chose continual quite deliberately instead of continuous to describe the type of improvement required within the EMS.
"According to the dictionary, continuous means ‘continuing without interruption,’ while continual means ‘steadily recurring.’ It would have been unreasonable and impractical to expect every organization to be constantly improving their EMS, ‘without interruption.’
"On the other hand, ‘steadily recurring’ improvement is a reasonable expectation for every EMS. Continual improvement of the EMS means there should be evidence the EMS is improving over time—that the overall trends should show improvement, even if there are incidents or times when improvement isn’t always occurring. This is an achievable expectation for any organization with an EMS."
Joe Cascio, chairman of the U.S. TAG ISO/Technical Committee (TC) 207, concurs with Jackson. In response to this topic, Cascio and his organization, Global Environment & Technology Foundation, described continual improvement as an ongoing process that is required even after the organization reaches "a desired level of performance." In addition, Cascio points out that the organization must show progress. Failure to show progress or intent causes the system to be deemed ineffective.
A slightly different opinion was provided by those in the quality arena. Jack West, chairman of U.S. TAG TC 172 said, "I think most would say it is best to use continual rather than continuous. On the other hand, with regard to the QMS, I do not think there is any intended difference."
West shared Cascio and Jackson’s understanding that "using the term ‘continuous’ means that improvement is actually happening at every instant in time, something that is very likely impossible. For this reason, it is likely that the word ‘continual’ has come into wide use; it seems to recognize the inherently incremental nature of improvement.
"From a practical point of view, improvement does tend to be the result of discrete actions or projects, so ‘continual’ is a better word to use. It is the word of choice in the ISO 9000 family for the same reasons that Sue Jackson points out." West believes, however, that "in common usage, the terms [continual and continuous] have identical meanings."
Kathy Hinton, president of Sunrise Consulting, stated, "I can honestly say I have never heard them used differently. In my experience, the two words are used interchangeably, with the same meaning." According to West, Hinton’s understanding and use of the terms is highly acceptable. Hinton’s experience has probably been the experience of others trying to work with and around the terminology.
The terminology’s future
Which term will be used in the future? Brumfield pointed out that the term continual was used in ISO 9001:2000.
"In reviewing ISO/CD 2 9001:2000, I noticed the words ‘continuing’ and ‘continual’ instead of ‘continuous’ in elements 5.1, 5.5.1 and 5.7," he said. "In ISO/CD 2 9000:2000 element 3.11, continual improvement refers to the actions taken to enhance the features and characteristics of products and/or increase the effectiveness and efficiency of processes used to produce and deliver them. Improvements are continual and not considered to provide final solutions."
It is acceptable to many to use continual and continuous interchangeably. The ISO standards specifically chose to use the term "continual improvement" because the developers understood it is impossible for improvement to occur uninterrupted.
Based on Cascio and Jackson’s response, continual improvement is required in an EMS and should occur over a period of time; however, the organization is only expected to show consistent progress, not continuous or uninterrupted improvement. Regardless of the flexibility being provided by the EMS standard, however, ISO 14001 registration is not a shield from the long and dreaded arm of the law, and noncompliances will continue to be subject to government sanctions.
The bottom line is that an EMS and a QMS should show a consistent progression toward improvement, with nonconformances being addressed quickly and effectively. Therefore, regardless of which of the two words you place in front of the word "improvement," the most important things to remember are that improvement should be an ongoing process, nonconformances should be dealt with immediately, and perfection is an endless pursuit, with many possible rewards along the way.
Compiled by Jack West
and Charles Cianfrani
Q: When you’re using time-stamped data and other discrete and continuous variables from other sources, what resource is best to help understand how to set up a 30-second timestamp data set? The 30-second facet isn’t the key characteristic. What I need to know is how to take data from other sampling rates while integrating event codes.
A: There are two kinds of events to consider: discrete and continuous. Discrete events have a category associated with them, such as a call failure code, which assigns a number to a certain type of call. For example, 3 indicates a successful call, while 4 indicates a dropped call (see Table 1). Continuous events have a numerical value, such as uplink signal strength (see Table 2).
To create a data set that has one row per sector per 30 minutes, you simply count the events for each discrete event in a given sector during that 30-minute interval. You can also add columns for absolute change in count and percentage change in count for each kind from the previous 30-minute period.
For continuous events, you simply take the minimum, maximum and average during the time period. You can also add absolute change or percentage change from the previous period. The result is one column for each discrete event value and three columns for each continuous event (see Table 3).
Professor, department of statistics
University of Central Florida
Senior partner, consultant
Jisc Consulting Inc.