Let’s get sampling!

In our earlier posts, we looked at what is a sample, why is it required, what is representativeness and accessibility of a sample and what are the criteria of sampling design.
Now we will look at the actual procedure of choosing a sample. While choosing a sample, we have to keep in mind all the things that we learned so far…i.e. the

Representativeness of a sample
Accessibility of a sample
Criteria of a sampling design

Referring to an earlier definition; the process of selecting individuals from a population is called sampling technique/ sampling strategy/ sampling design

We will deal with 2 basic types of sampling today:-
First is
Simple random sampling – this is a technique of sampling that is the easiest and many of us may be practicing it in our daily lives.
Take the example of a simple lucky draw at a program with a live audience. The lucky draw decides who from the audience gets a surprise gift. The names of all the individuals in the audience are written down on chits, collected and a chit from that is picked up by the show host. S/he reads the name on the chit and that person gets the gift! This is exactly what simple random sampling is all about, and this is how it is carried out.
The drawing of the chit done in this case though was to decide who will win the gift, but in sampling it decides who all will be included in the sample.

Suppose if out of a population of 250 students 50 is decided as number of participants in the sample. Then to randomly choose from these 250 a sample of 50 students, a list of all 250 students would have to be made, put on chits referring each one by a unique number or their names, then a name would be drawn which would be noted in a column named sample and that chit would not be placed back with the others. This would have to be repeated 50 times till 50 names are gathered for the sample. The names written down in this column would now be collectively considered as sample. Here;
The 250 individuals / or the list of the population = sampling frame
The 50 names / list of individuals selected from the population = sample
This method is also called as the lottery method. The use of random number table is also made to select the number of individuals required as subjects from the sample. You can visit the following link to read further how to use a random number table.

Take me to the random number table

This type of sampling is characteristic of the fact that it allows every item/individual a chance to be selected in the sample. Thus bringing in the representativeness aspect of sample and that it is selected without bias. The fact that the items/individuals are selected at random or chance shows that the selection was without any bias. And because of all these characteristics, the results obtained from such a sample will be genralisable to the population.
The only disadvantage with this type is that a complete list of all items/individuals within the sampling frame is required which may not be readily available. And incase of larger populations listing every person and then choosing via the lottery method would be too cumbersome. Hence this type maybe suitable to populations which are easy to handle and list.

The second type of sampling we’re going to deal with today is,
Convenience sampling
The name itself says volumes about the type of sampling. It deals with choosing the nearest individuals to serve as sample participants or items, until the desired number is reached. Simply those individuals are chosen who are easily accessible.

A sample selected in such a way however will not be able to give results which will apply to the wider population. Also only those individuals have a chance of getting selected who are easily accessible or come in contact with the researcher ruling out the possibility of others getting selected in the sample. Hence the results of a study using such a sample will be applicable only to that group. Because of the nature of this type it has other names like accidental sampling or opportunity sampling. Such a type of sampling can be used in case study method of research.
After going through these two types of sampling, I have a small task for you:
What you need to do is write down any noticeable differences in the two and write them as a comparison of the two types in the form of a post in your respective blogs.
I want at least two major differences that YOU come out with and not Google ;)
You could put up your posts uptil tomorrow.