FIC0154 Basic Communication Research ( 2 December-9 December 2012)
Online Discussion Question
Reference materials: Lecture on Sampling and relevant text book chapters
1) What is the difference between probability and nonprobability samples? Explain in your own words and give examples of each type of sample.
Answer: A probability sample is selected according to mathematical guidelines whereby each unit's chance for selection in known. This will be more complex and every unit has a equal chance to be pick up.
Example of Probability Samples:
i) Random Sample: The researcher may listing the name list and pick a desired sample from a population by including every subject in the population in a box and randomly drawing from it to form a sample.
ii) Systematic Random Sampling: The researcher may pick up a sample from the list of a randomly arranged population by following the systematic number such as multiple of 2 or even number.
iii) Stratified Sample: A proportionate population is determined, and that population is divided into groups with various variables. Then, samples are randomly picked from every group.
iv) Cluster Sampling: Dividing smartphone users from a campus into groups according to their course, and randomly selecting samples from those groups.
A nonprabability sample sample does not follow the guidelines of mathematical probability.This will be more easier and it do not care whether the unit have how many chances to be pick up.
Example of Nonprabaility Sample:i) Available/ Convenience Sample: Selecting the sample randomly from a group pf teenagers in a school.
ii) Volunteer Sample: Picking up the sample from a group of passengers by selecting those who willingly volunteer participate in the research.
iii) Purposive Sample: The researchers are conducting a research on shampoo will pick up only with long hair as they are relevant to the research, instead of choosing people who no hair.
2) What are the advantages of choosing a probability sample in your research?
Answer: i) Every unit has a equal chance to be pick up.
ii) The sample carry grater value.
iii) It is more accurate because the whole population has a chance being selected.
iv) It able to calculate the sampling error with the formula when the error exists.
What are the advantages of choosing a nonprobability sample in your research?
Answer: i) The sample is easier to select.
ii) It is more convenient.
iii) Nonprabalility sampling is less time consuming.
iv) Nonprobability samples is lower in cost.
3) If you want to do a Random Cluster Sampling of 10 people out of this entire class, how should you go about it?
Answer:
Example Sampling Fame: A whole class of 200 people.
i) First, cluster the entire class into 3 groups according to the race: Chinese, Indian and Malay.
ii) From the 3 groups, randomly select a group and re-cluster the selected group into another 3 groups according to the religion. Such as if the selected group happens to be Chinese: Buddhist, Christian and Others.
iii) Next, randomly pick up 2 groups from the 3 groups and randomly pick up 6 people from each of the selected 2 groups.
4) If you want to do a Random Stratified Sampling of 10 people- 7 females, 3 males- out of this entire class, how should you go about it?
Answer:
Example Sampling Fame: An entire class of 100 people.
i) First, get a name list of the whole class and divide it into 2 groups: Males and Females.
ii) From the Males group, randomly select 3 students of it.
iii) From the Females group, randomly select 7 students of it.
5) What is "Sampling Error", in your understanding?
Answer: The difference of measurement between sample and population.
Posted by:
Ong Jia Min ( Carmen) 0310699
