Polietapic sample desing

What is a polietapic sample design?
A sample design polietápico is a type of design research project to collect data from a survey which is divided into various stages of planning and implementation.
These stages cover various criteria that are deployed to reach the final sample, or to individuals that will finally answered the survey.
Let us remember that a sample is a part of a specific population or universe (e.g. a country or a city citizens) is selected to obtain information that will be generalized to the whole population with some margin of error.
As a result, when according to rigorous methodological guidelines, the sample will be representative of this population.
To make this happen, the universe will be successively divided according to different criteria to reach the people you select.
For example may split the provinces or States of a country and select some rightly gaming, dodging, and then in selected provinces applied with a proportionality to the population parameters selection criterion.
If there are 10% of high socio-economic level in the population, determining the sample shall be about that value.