There are two main types of sampling: probability sampling and non-probability sampling. Probability sampling involves methods where the probability of selection of each individual is known, such as simple random sampling, systematic random sampling, stratified random sampling, and cluster random sampling. Simple random sampling involves selecting a sample that gives each individual an equal chance of being selected by identifying the population, determining sample size, listing all population members, assigning them numbers, selecting numbers at random from a table, and including individuals in the sample if their number is selected. The advantages are it is easy to conduct and requires minimum population knowledge, while disadvantages include needing all population member names and potential over or under representation.

1. Types of sampling
Probability sampling Non probability sampling
Probability of selection of
each individual is known
and pre determined
Simple random sampling
Systematic random sampling
Stratified random sampling
Cluster random sampling
Multistage random sampling
Probability of selection of
each individual is not
known
Quota sampling
Purposive/ Judgmental
sampling
Snowball/ Network sampling
Convenience/ Grab sampling
(man in the street)

2. SIMPLE RANDOM SAMPLING
The proces of selecting a sample that
allows induvidual in the defined
population to have an equal and
independent chance of being selected
for the sample.

3. STEPS IN RANDOM SAMPLING:
1. Identify and define the population.
2. Determine the desired sample size.
3. List all members of the population.
4. Assign all individuals on the list consecutive
number from zero to the required number.
Each individual must have the same number
of digits as each other individual.

4. STEPS IN RANDOM SAMPLING:
5. Select an arbitrary number in the table of
random numbers.
6. For the selected number, look only at the
number of digits assigned to each population
member.

5. STEPS IN RANDOM SAMPLING:
7. If the number corresponds to the number
assigned to any of the individual in the
population, then that individual is included
in the sample.
8. Go to the next number in the column and
repeat step #7 until the desired number of
individuals has been selected for the
sample.

6. ADVANTAGES OF SIMPLE
RANDOM SAMPLING:
 Easy to conduct
 Strategy requires minimum
knowledge of the population to be
sampled

7. DISADVATAGES OF SIMPLE
RANDOM SAMPLING:
 Need names of all population members.
 May over-represent or under-estimate
sample members.
 There is difficulty in reaching all selected
in the sample.