Chapter 15 - Types of Data

As discussed in Chapter 4, the DataFerrett is capable of tabulating several types of data. The basic descriptions are listed below.

Microdata

Microdata is data in which every record is at the unit of analysis level and all records must be added up to get the totals for each data item. For example, for surveys of individuals, microdata contain records for each individual interviewed; for surveys of organizations, the microdata contain records for each organization.

Aggregate Data

Aggregate data is data which has already been summarized or added up, usually for specific geographical units or some other unit, such as industry classifications. In this case, each record is a geographical unit and there is no summing needed to get the totals for the geographies.

Time Series Data

Time Series Data is a sequence of observations which are ordered in time (or space). If observations are made on some phenomenon throughout time, it is most sensible to display the data in the order in which they arose, particularly since successive observations will probably be dependent. Time is called the independent variable.

Longitudinal Data

Longitudinal Data is a panel data in which many units are observed over multiple time periods. The Bureau of Labor Statistics' National Longitudinal Surveys (NLS) program collects data from a particular age group of people over many years on an annual or biennial basis. The panel data track the same sample of individuals over many time periods.