Are quatiles and deciles useful when applied in a real life situation? thanks
In real life, there are situations when we want to know the strongest, weakest, largest, smallest, top, bottom values in given large amount of data. When you have a large amount of data, you want to understand a certain part of that spread and make the necessary actions after. If you want to partition the data into ten equal parts, then you have a decile.
We do this in standardized exams, income distribution and in investments. For example, academicians would want to know how the youth of the nation fare compared to the countrys standards of quality knowledge acquisition. If the top 20% percent of the high scorers are in the first decile, it gives a hint to the education department that the teachers, curriculum experts are doing a great job in the delivery of their work because the test-takers fared well. In the case of income distribution, if the top 10% of the wage earners are in the 8th decile, it gives a hint to the government to do something to increase their earning power.