The Psychology of Quality and More

A Toolbook for Quality Improvement and Problem Solving (contents)

The purpose of measuring

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Objectives | Purpose

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Objectives

In any problem-solving or tool-usage situation, a desirable outcome may be described in the form of a statement of objectives. Sometimes this is implicit, but it is usually worth writing down in a short sentence, as this will help to achieve consensus within the project group, acting as a 'guiding star' for decisions and actions. One of those actions will be the collection of data in order to demonstrate whether objectives have been met. It makes sense if the statement is worded in a way that helps that data to be clearly identified.

For example, when setting the objective of an improvement project, the specifics of what is to be improved may be included in the objectives statement, such as, 'Increase the accuracy and timeliness of the order processing system'. In this case it is clear that accuracy and timeliness must be measured.

Questioning

When planning a project, even when using objectives, it may not always be clear what should be measured. A simple and effective approach to this is called the goal-question-metric paradigm, which uses a question as a bridge between objectives and measures. The approach is to ask questions about objectives that may help measures to be identified, particularly 'How will I know how well the objective is being approached?' and 'How will I know when the objective has been met?'. Other useful measures may be found by asking questions such as: 'How many?', How much?', 'When?', 'How useful?', 'How expensive?', 'How often?', 'Who?'.

For example, if the objective is 'make a better cake', then the questioning step may ask, 'How will I know a better cake?' and 'Who can tell me?', which then leads to measures such as comparison against a benchmark or focus group consensus.

Purpose

In measuring any process, there are two common reasons why measurements are made, being either an ongoing monitoring measurement or a more specific investigative one.

Monitoring measurement

Monitoring measurements act as indicators of the general health of the process, much as temperature gives an overall indication of the health of the human body. The measurement is made over a long period, so that trends and variation can be understood and points where specification limits or target values are exceeded may be identified.

Several considerations should be taken into account when identifying monitoring measurements:

• The measurement should identify the presence of problems, but not necessarily the cause. Breadth is thus more important than depth.
• The measurement should not be intrusive or upset the process in any way, as objective decisions can only be made through independent observation.
• Each measurement should be repeatable and made under similar conditions, so they may be compared on an equal footing.
• It should be possible for measurements to be made on a regular basis. This is easy where the process repeats frequently, such as on a production line, but can prevent identification of trends, etc., in processes with longer cycles, such as new product introductions.
• As it is made frequently, the measurement should be relatively inexpensive and easy to perform.

Investigative measurement

Investigative measurements are made specifically to find out more about known problems or causes. This may be likened to specific medical tests such as measuring blood pressure. The limited nature of an investigative measurement means that it may differ from monitoring measurement in several ways:

• The measurement may be intrusive.

• The cost of measurement is not particularly important.

• Many different measurements may be made, where each measurement covers a specific area in more detail.

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