Sampling is a method of obtaining information from a subset of a larger population to make estimates, which is often faster and cheaper than surveying the entire population. It can be conducted using probability or non-probability techniques, with various methods like simple random sampling and stratified random sampling. While sampling reduces costs and field time, it may also introduce random errors if the sampling frame is large or lacks research expertise.

2. The process of obtaining information from a subset(sample) of a
larger group(population).
The results for the sample are then used to make estimates of
the larger group.
Faster and cheaper than asking the entire population.
SAMPLING

3.  Get information about populations
 Reduce cost of research
 More accuracy of results
 Less field time
 Generalize about population
 When it’s impossible to study the whole population
WHY SAMPLING?

4. Technical Terms
• A sampling frame is a list of sampling units.
• A sample is a collection of sampling units drawn
from a sampling frame.
• Parameters: numerical characteristics of a
population
• Statistic: numerical characteristic of a sample

5.  Probability Sample:
A method of sampling that uses of random
selection so that all units/case in the
population have an equal probability of
being chosen.
 Non-Probability Sample:
Does not involve random selection and
methods are not based on the rational of
probability theory
Sampling Techniques
Probability Non-Probability
TYPES OF SAMPLING

6. Probability SAMPLING
Following are some commonly used sampling
methods:
• Simple Random Sampling
• Stratified Random Sampling
• Cluster Sampling
• Systematic Sampling

7. SIMPLE RANDOM SAMPLING
Application when population is small,
homogeneous & readily available
All subsets of the frame are given an
equal probability. Each element of the
frame thus has an equal probability of
selection. A table of random number or
lottery system is used to determine
which units are to be selected.

8. Possible Ways To Do Sampling
• The sampling units are chosen with
replacement in the sense that the chosen
units are placed back in the population.
• The sampling units are chosen without
replacement in the sense that units are
chosen are not placed back in the
population.

9. Properties of Sample Distribution

10. Advantages:
• Easy method to use
• No need of prior information of population
• Equal and independent chances of selection to every
element
Disadvantages:
• If sampling frame large, this method impracticable.
• Does not use researcher’s expertise .
• Larger risk of random error