Data Organisation: Tally Marks, Grouped Distributions & Class Intervals
1. Data Classification Terminology
- Raw Data: Unorganised collection of numerical observations.
- Range: Difference between highest and lowest observation: $\text{Range} = X_{\text{max}} - X_{\text{min}}$.
- Class Interval ($a - b$): A grouped range where $a$ is the Lower Limit and $b$ is the Upper Limit.
- In continuous grouping ($0-10, 10-20$), the upper limit is excluded from that class and included in the next ($10$ belongs to $10-20$).
- Class Size / Width: $\text{Width} = \text{Upper Limit} - \text{Lower Limit}$.
- Class Mark (Midpoint):
$$\mathbf{\text{Class Mark} = \frac{\text{Upper Limit} + \text{Lower Limit}}{2}}$$
GROUPED FREQUENCY TABLE ARCHITECTURE
Class Interval Tally Marks Frequency (f) Class Mark (x)
0 - 10 |||| 4 5
10 - 20 |||| || 7 15
20 - 30 |||| |||| 9 25
30 - 40 |||| 5 35
