Data are measurements or observations that are collected as a source of information. There are a variety of different types of data, and different ways to represent data.
The number of people in Timor-Leste, the countries where people were born, number of calls received by the emergency services each day, the value of sales of a particular product.
A data unit is one entity (such as a person or business) in the population being studied, about which data are collected. A data unit is also referred to as a unit record or record.
A data item is a characteristic (or attribute) of a data unit which is measured or counted, such as height, country of birth, or income. A data item is also referred to as a variable because the characteristic may vary between data units, and may vary over time.
An observation is an occurrence of a specific data item that is recorded about a data unit. It may also be referred to as datum, which is the singular form of data. An observation may be numeric or non-numeric (categorical). For example, 173 is a numeric observation of the data item ‘height (cm)’, whereas ‘Timor-Leste’ is a non-numeric (categorical) observation of the data item ‘country of birth’.