Give an example of each

Question

1) Simple random sample

2) stratifed sample

3) systematic sample

4) cluster sample

5) covenience sample

Answer 1

Step 1:

(1)

Simple random sample:

Simple random sample refers to sampling method which has following properties.

1) The population consist of objects.

2) The sample consist of objects.

3) If all possible sample of objects are equally likely to occur, the sampling method is called simple random sample.

Example :

One of the example is Lottery method.

Each of the population is assigned to a unique number. The numbers are placed in a bowl and mixed.

A person selects numbers. Population member having the selected numbers are included in the sample.

Step 2:

(2)

Stratified sample:

A stratified sample is a population sample that requires the population to be divided into smaller groups, called strata.

Example :

A company has 200 employees in four categories.

Managers : 25

Production staff : 55

Administration staff : 120

How many from each category are selected in a stratified sample of size 20.

Here in the above example Managers, Production staff and Administration staff are strata.

Now to find the stratified sample of size 20, we find the number of members from each strata.

Sum of all gives the sample of size 20.

Answer 2

Contd...

Step 3:

(3)

Systematic sample:

With systematic random sampling, create a list of every member of the population.

From the list, we randomly select the first sample element from the first  elements on the population list.

Thereafter, we select every element on the list.

The period of the systematic sample is calculated as .

Example :

Consider a researcher need a sample of size 10 from the population of 100.

 Select a first random sample number as 6.

Periodicity is . Now repeat the numbers with periodicity of 10.

Sample is 6, 16, 26, 36, 46, 56, 66, 76, 86, 96.

Step 4:

(4)

Cluster sample:

A cluster sample is a population sample that requires the population to separate groups, called clusters.

Example :

The researcher requires academic performance of high school in United states of America.

So first we divide this in terms of geography, there are 50 states in the USA.

Now we select samples of students of high school in each and every state using systematic sample or simple random sample.

Step 5:

(5)

Convience sample:

A convenience sample is one of the main types of non- probability sampling method.

A convenience sample is made up of people who are easy to reach.

Example :

Selecting 5 people in a class

Selecting 5 names from the list of patients.