Data are classified into two main types, primary and secondary data. In addition, this data may be qualitative or quantitative
- Primary data is information that is collected first-hand by those conducting the assessment. This type of data would include original information gathered through surveillance activities, focus groups, interview and observations.
- Secondary data is information that has already been collected by someone else. Often secondary data already have been analyzed and disseminated and can be used without any additional calculations. An example of this available in County Profile or other sources. Sometimes secondary data with some analysis completed e.g. death certificate data has to be combined with population estimates to get rates, or may be available in unanalyzed or raw form.
- Quantitative data are based on numbers and often are called "statistics". Examples include cancer deaths, infant mortality rates, participants responses sorted in 'yes' or 'no' categories in surveys.
- Qualitative data is non-numerical, and is often presented in narrative form. Examples are descriptions of services or programs based on participant observation, barriers to care described by participants or providers.