How do I take a sample and compute an estimated number that

How do I take a sample and compute an estimated number that would correctly respresent the population?

Solution

The answer to your question lies in sampling tehniques. These tecchniques are largely determined by the application at hand. There are some topics which should be clearly defined once we want to sample:

1. The selection method for the elements of the population (sampling method to be used).

2. Sample size.

3. Reliability degree of the conclusions that we can obtain, this is, an estimation of the error that we are going to have (in terms of probability).

a non appropriate selection of the elements of the sample can cause further errors once we want to estimate the corresponding parameters in the population

We always make probability sampling, because in case we choose the appropriate technique, it assures us that the sample is representative and we can estimate the errors for the sampling. There are different types of probability sampling:

• Random sampling with and without replacement.

•Stratified sampling.

• Cluster sampling.

• Systematic sampling.

• Other types of sampling techniques

each are used in different scenarios.For details you can use wikipedia also.