Question

what makes the participants of a study a good/bad sample of the population?

Answer 1

It is often impractical to study the whole population. In that case we take a sample from that particular population which infer some information about the entire population.

Now what this sample made of? This sample is made of participants ( people) or any objects. So these participants in the sample play a major role here.

This selection of participants in the sample actually speaks about the whole population. We say that the sample is good, when it actually predicts / estimates / describes the complete population well or its parameter. We say the sample is bad, it means that it failed to describe the complete population.

So selection of these participants in the sample should be done in a correct manner. More well the participants selected, more well the sample can predict the population. From a study of good sample, we can estimate the characteristics of the entire population because sample possesses the characteristics of a population.

Example-

Suppose we want to estimated the average annual income of a country. Now if we only select the incomes of CEOs, Managers, Industrialists or from porsh areas, then out sample will be bad and it will give us a high average annual income which is wrong.

Instead, we have to take incomes of workers in every field. From a farmer earning 1lakhs per annum to a business man earning 10 crores per annum, from every fields values have to be taken to study well. Always remember as the sample size increases , better it can predict.

So selection of participants should be unbiased and should be taken from every corners of the population.

................................................................................

Thanks for the problem. Please support me with a like if I deserve and let me know if you have any doubt. Thanks