Question

b) How can each of the following sampling techniques be biased? Give an example.

-Multi-stage Sample -Voluntary Sample -Convenience Sample

Answer 1

Multistage sampling technique is defined as method that divides the population into groups and then collect the sample. This sampling technique divide the population into groups and then divide into sub-groups at stages to collect the data for research.

For example, if we need to know the expenditure on milk in USA through call. We can choose 300 members in sample as follows :

At first, we can choose the number of states using any probability sampling method. For example, select fifteen states.

Then, choose four districts within each state using any probability sampling method.

And, at the end we can choose five persons from each district using any simple random sampling method. We will get 500 persons that we can include in the sample group for research.

Disadvantage:

It is not as accurate as simple random sampling when the size is same.

In multistage sampling some portions of the population data is left out so its not completely representative of the population.

Convenience sampling is a sampling technique which uses sample data that are close to hand. It is a non-probability sampling method where sample is chosen based on easy to reach or contact.

For example Convenience sampling is often used by students to get any information by creating questionnaire and sending that to their contact list.

Disadvantage:

It is not representative of the population.

It is not random and based on conveniece to collect data.

It can not be generalized for the population.

Voluntary response sampling is defined as a technique in which sample is made up of self-chosen participants. In this sample people are those who are volunteering to take part in the research.

For example people are asked to participate in a poll about any topic. But they are choosing to participate or not is based on their choice.

Disadvantage:

People selected in the sample are not representative to the population.

People are having strong opinion on the topic are most likely to participate.