Assignment No.2 (Dispersion)
1. Concept of Population and Sample
Population
Population means the complete group of people or items that we want to study.
In simple words:
Population = All members of a group
Examples
All students in a university
All citizens of Pakistan
All workers in a company
Example:
If we want to study marks of all students in a class, then all students are the population.
Sample
A sample is a small part of the population selected for study.
Researchers study samples because studying the whole population is difficult and expensive.
Examples
Surveying 100 people out of 5000 people
Studying 50 students from a university
Example:
A college has 1000 students, but we study 100 students.
Those 100 students are the sample.
2. Measure of Dispersion
Definition
Measure of dispersion shows how much the data values spread out from the average (mean).
In simple words:
It tells us how different the values are from each other.
Example
Data Set A: 10, 10, 10, 10
Data Set B: 5, 10, 15, 20
Both averages are 10, but data set B has more spread.
So dispersion is greater in B.
Uses of Dispersion
1. Shows variation in data
2. Helps compare two data sets
3. Shows reliability of the average
4. Used in business, economics and research
Examples of dispersion:
Range
Mean Deviation
Variance
Standard Deviation
3. Mean Deviation
Definition
