01 · TYPES OF DATA
Primary & Secondary Data
DATA CATEGORIES
Data Collection Types
• Primary Data: Data collected directly by the investigator first-hand for a specific purpose (e.g. counting absences in a class).
• Secondary Data: Data obtained from an already published source or database (e.g. census records, newspaper reports).
02 · FREQUENCY DISTRIBUTION TABLES
Ungrouped & Grouped Frequency Tables
To make large raw data understandable, we group data into class intervals (e.g. 0–10, 10–20, 20–30).
• Class Size: Upper limit - Lower limit (e.g. 20 - 10 = 10).
• Class Mark: (Upper limit + Lower limit) / 2.