Data is a set of facts expressed in quantitative form. It can be primary or secondary. Data collection is the first step for statistical studies.

2. Introduction
General characters
Definition
Example
Sources

3. Type of data

4. 4
General characters
 First hand information
 Original
 Reliable
 Consumes more money
 No extra precautions are needed
 Raw data
 Investigator must be well trained

5. 5
Definition
Data originally collected for investigation are
known as primary data

6. Example
 Censuses conducted by government agencies
 Amount of O2 estimated by student

7. 7
Sources
 Direct personal investigation
 Indirect oral investigation
 Information through correspondents
 Questionnaire method