If you are asking about sample size selection, you can use: http://www.tools4dev.org/resources/how-to-choose-a-sample-size http://www.tools4dev.org/resources/h

If you are asking about sample size selection, you can use: http://www.tools4dev.org/resources/how-to-choose-a-sample-size http://www.tools4dev.org/resources/how-to-choose-a-sample-si... If you want to evaluate quality of a sample, that's an entirely different issue. You may want to look up different sampling methods.