A data element concept is the combination of one object class and one property. It describes who or what is being looked at, and what it is about them which is being recorded.

The way the data element concept is represented in the collected data is not specified – so the unit of measurement, list of possible codes, or the format of a potential string of characters is not included. These elements are described in a value domain. Once a value domain is combined with a data element concept, it then becomes a full data element. The data element concept is just stating the idea of what is being studied. Hence the name 'data element concept'. It’s the conceptual part of a data element.

Some examples of data element concepts are:

Birth—birth weight – the thing being looked at here is a birth of a baby, and the aspect or property being recorded is the baby’s weight at birth. No weight units are specified here – those come in when the value domain is added to the full data element.

Address—Australian postcode – the thing being looked at is a person’s address, and the property, or aspect, about their address being collected, is their postcode in Australia.

Patient—principal diagnosis – the thing being looked at here is a person who is a patient, and their main medical diagnosis is the thing, or property, about them that’s being recorded.

Service provider organisation—hours worked by volunteer/unpaid staff – the thing being looked at here is an organisation that provides services, and the property being collected is how many hours are worked by their volunteer or unpaid staff.

Data element concepts are modular, and can be combined with a range of value domains to create different data elements. For example, the data element concept Person—age can be combined with two different value domains – age in months N[N], and age in years N[NN], to come up with data elements that describe a person’s age in months, or in years:

• Person—age, total months N[N]
• Person—age, total years N[NN]