A distinct piece of information in the form of fact or figures collected or represented for any specific purpose is called Data.
Collection of Data
Data are generally of two types
- Primary Data
- Secondary Data
- Data collected from any first hand experience for an explicit use or purpose is known as Primary Data
- Data collected by any third party for a different purpose other than the user is known as Secondary Data.
- The number of times a particular instance occurs is called frequency in statistics.
- Ungrouped data is data in its original or raw form. The observations are not classified in groups.
- In grouped data, observations are organized in groups.
- The size of the class into which a particular data is divided.
- E.g divisions on a histogram or bar graph.
- Class width = upper class limit – lower class limit
Regular and Irregular class interval
- Regular class interval: When the class intervals are equal or of the same sizes.
E.g 0-10, 10-20, 20-30….. 90-100
- Irregular class interval: When the class intervals are of varying sizes.
E.g 0-35, 35-45, 45-55, 55- 80, 80-90, 90-95, 95-100
- A frequency table or distribution shows the occurrence of a particular variable in a tabular form.
- Raw data needs to be sorted in order to carry out operations.
Ungrouped frequency table
- When the frequency of each class interval is not arranged or organised in any manner.
Grouped frequency table
- The frequencies of the corresponding class intervals are organised or arranged in a particular manner, either ascending or descending.