Dimensional Sampling

Lets explore types of sampling:

Dimensional sampling is one of the type of non-probability sampling. It is an extension to Quota sampling.

Meaning:
Dimensional sampling is a sampling technique for selecting small samples in a way that enhances their representativeness. It involves identifying various factors of interest in a population and obtaining at least one respondent of every combination of those factors. The researcher takes into account several characteristics such as gender, age, income, residence, education and ensures there is at least one person in the study that represents that population.

Steps:
There are two steps to dimensional sampling.

1. Specify all the dimensions or variables that are important.
2. Choose a sample that includes at least one case representing each possible combination of dimensions.

Examples:

1. Out of 10 people researcher may want to make sure that 2 people are within a certain gender, two are of certain age group who have an income rate between Rs. 125000 and Rs. 300000. This will ensure the accuracy of the sample frame again.
   
2. A researcher may be interested in studying disaffected students, girls and secondary aged students and who may find a single disaffected secondary female student, i.e. a respondent who is the bearer of all of the sought characteristics. (Cohen, 2003)

References:

http://www.learnmarketing.net/sampling.htm

http://www.uic.edu/classes/socw/socw560/Sampling1.htm

Cohen Louis, et al. (2003). Research Methodology in Education. 104. London: RoutledgeFalmer.

Priyanka Joshi (6)

Nilambari Rane (16)

Day - 5

IS randomness only of ONE type??

The difference between two examples is in the selection of sample though it is selected randomly:

First Example:

• The method of research is survey
• 300 primary schools are selected from total 1000 primary schools

Second Example:

• The method of research is experiment method
• Whole population is randomly selected by making two groups of them.

The both examples are as follows for the reference:

1. A researcher wants to find out the opinion of primary school teachers on the increasing amounts of size and weight of children’s’ schoolbags. She decides to carry out a survey for this purpose. Out of the 1000 primary school teachers in Mumbai, she decides to select 300 teachers randomly for her study.
2. A teacher at a university wants to find out whether there is any difference caused in the academic achievements of students after using 2 different kinds of CAI packages - one with linear interactivity and the other with non-linear interactivity. She decides to carry out the study on her own batch of 50 students. Since there are 2 kinds of CAI packages to be implemented, she makes 2 groups in the following way:She lists everyone’s names on chits, and draws one chit out of the lot and writes that name under a column named linear CAI and puts that chit aside. Then she picks another one, this time writing the name under a column named non-linear CAI. She proceeds in this way until all chits have been randomly distributed under the 2 columns and she is ready with 2 groups of students for her study.

Day 4

- Let's get sampling

Difference between Simple Random Sampling and Convenience Sampling

Simple Random Sampling

• Meaning - The sample is selected on purely simple random basis. Every individual has an equal chance of getting selected from the required population for a particular study. The sample is selected through a draw method which we have seen in many game shows where the chits are made of the whole population and any chit is picked up for announcing the winner.


• Other name – Lottery method


• Representativeness - The sample is representative.
  
• Threat - The sample may not be accessible to researcher, but the results are generalisable.

Convenience Sampling

• Meaning - The sample is selected as per the convenience to the researcher. The individual who is easily accessible to the researcher is selected as a sample from a required population for a particular study.


• Other name - accidental sampling or opportunity sampling


• Representativeness - The sample is not at all representative.


• Threat - The results of the study are not generalisable as the sample is selected on purposive basis.
  

Link of images - http://images.google.co.in/imgres?imgurl=http://www.newtekpro.com/ArtGallery/2002/03/dice.jpg&imgrefurl=http://www.ghettodriveby.com/dice/&h=480&w=640&sz=35&hl=en&start=1&tbnid=QRO5lzNp_is2xM:&tbnh=103&tbnw=137&prev=/images%3Fq%3Ddice%26gbv%3D2%26svnum%3D10%26hl%3Den

http://images.google.co.in/imgres?imgurl=http://www.msu.edu/~cua/PUBS%2520Jan%2520June%25202000/world%2520hands%25202.gif&imgrefurl=http://www.msu.edu/~cua/PUBS%2520Jan%2520June%25202000/step_5_Month_4.htm&h=364&w=412&sz=10&hl=en&start=1&tbnid=nxmU-QJ3KokgHM:&tbnh=110&tbnw=125&prev=/images%3Fq%3Dconvenience%2Bsampling%26gbv%3D2%26svnum%3D10%26hl%3Den

Quotes

"Remember not only to say the right thing in the right place, but far more difficult still, to leave unsaid the wrong thing at the tempting moment." - Benjamin Franklin

“If you have an apple and I have an apple and we exchange these apples then you and I will still each have one apple. But if you have an idea and I have an idea and we exchange these ideas, then each of us will have two ideas.” - George Bernard Shaw

Day 3

- Criteria of sampling design- GO Measure Practical Economy!

As far as I can understand the first unlabelled picture refers to timing and other refers to representativeness of sampling. But Hemangi, I am a bit confused about the question? I don't know what exactly am i supposed to do.

Day 2

- Accessability of a sample

Hi Hemangi, I read the 98-99 pages of the book Research Methods in Education by Louis Cohen and Lawrence Manion. The explanation given about the access to the sample is very comprehensive.

The examples that I can think of about the problems, a researcher might face in accessing a sample are:

1. The students who have high security around them as their parents are important personalities of the country or are celebrities. Research may be whether these students make their group with other socio-economic class students or not. Limitation to the sample is that the sample has high security around them which sometimes restricts access to them for researcher.
   
2. Research on the scholastic achievement of the students who always travel from one place to other due to the job transfer of their parents. Limitation to the sample is, the sample may not stay at one place for more than one year.
   
3. Survey on the personality development of the students who are grown up single-handedly due to the divorced parents. Limitation to the sample is, the sample themselves don’t want to speak about their relationship with parents which has directly affected to their personality development. (On page 99 of the said book the reason given for this is that the sample sometimes fears to get embarrassed by giving some confidential information)
   

I hope that these examples satisfy the question you asked.