When even phenomena happen, that is due to many causes, but all these causes can not be expressed in terms of data. So we cannot reach at the correct conclusions. Development of a group depends upon many social factors like, parents’ economic condition, education, culture, region, administration by government etc. But all these factors cannot be placed in data. So we analyse only that data we find quantitatively and not qualitatively. So results or conclusion are not 100% correct because many aspects are ignored.