The word 'data' means information in the form of numerical figures or a set of given facts. It can be anything, that is, numbers, words, measurements, observations or even just descriptions of things. There are two types of data: Quantitative and Qualitative.
i. Quantitative (or Numerical) data:
The data which are identified or measured on a numerical scale is known as Quantitative data or numerical data. Ex: Number of students appearing for an AP Statistics examination, the daily temperatures in Death Valley, etc.
Quantitative data can either be discrete or continuous.
The data are said to be discrete, if the values or observations belonging to it are distinct and separate, that is, they can be counted. Ex: Number of members in a family.
The data are said to be continuous, if the values or observations belonging to it are measured or take on any value within the finite or infinite interval. We can count, order and measure continuous data. Ex: Weight, height, temperature, etc.
ii. Qualitative (or Categorical) data:
Qualitative or categorical data are the data that can be classified into a group.
A set of data is said to be a categorical, if the values belonging to it can be sorted according to category. Ex: Gender, eye color, ethnicity, etc.
Qualitative data can be either nominal or ordinal.
The data in which there is no natural order between the categories is known as nominal data. We can count but not order or measure nominal data. Ex: Color of an eye.
The data in which an ordering exists between the categories is known as ordinal data. We can count and order, but not measure ordinal data. Ex: Auto racing.