Randomness can be different!

This post is in reference to the post by Hemangi named: IS randomness only of ONE type?? at http://metca6research.blogspot.com/2007/04/is-randomness-only-of-one-type.html

Difference in random sampling

• Example 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.

The difference in this example in sampling:
The researcher in this example has chosen a survey research method.

The sample is randomly selected through simple random sampling.

In this example, the sample is selected randomly out of 1000 primary school teachers in Mumbai 300 are randomly selected. So the sample is representative of the population.

In this there is only one group

The Results of this research are generalizable to all the population of 1000 primary school teachers as random sampling is done.

• Example 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.

The difference in this example in the sampling technique used is:
The reseracher here has chosen the experimental method of research.

The samples are first chosen through convinence sampling technique, & then the researcher used the simple random sampling technique in order to form 2 groups. The whole population is the sample itself.

There are 2 groups of samples.

The results of this research is generalizable only to that group.