Because without representative sample, your results will not be valid.
A sample that accurately reflects the characteristics of the population as a whole
Take a simple random sample.
A representative sample is one where the statistics of the sample are the same as the statistics for the parent population.
Well, if your sample does not represent the larger sample, you'll certainly not get a valid result ... For example, if you're studying pregnancy and your sample includes men - The whole idea of "representative' sample is fuzzy and often gives interesting errors.
The purpose is to obtain a statistical representative sample from the material to be tested.
Many statistical statements for a population which are based on a sample are not valid if the sample is not representative.
Lawrencium is very difficult to obtain and only in quantities of some atoms.
Because without representative sample, your results will not be valid.
A representative sample is a randomly selected subset of the population.
A simple random sample.
A sample is any subset of the total population. A representative sample is one that is chosen so that its characteristics are similar to that of the population.
A sample that accurately reflects the characteristics of the population as a whole
It is called a representative sample.
Take a simple random sample.
That the key characteristics of the population are reflected in the sample.
A representative sample is one where the statistics of the sample are the same as the statistics for the parent population.