how to calculate a decile
there is no one way of calculating a decile however it is important that you are consistent with whatever formula you decide to use to calculate a decile one simple calculation of a decile is d1 value of n 1 1 0 th data begin aligned text d1 text value of left frac n 1 10 right text th data end aligned d1 value of 10n 1 th data d2 value of 2 n 1 1 0 th data begin aligned text d2 text value of left frac 2 times n 1 10 right text th data end aligned d2 value of 102 n 1 th data d3 value of 3 n 1 1 0 th data begin aligned text d3 text value of left frac 3 times n 1 10 right text th data end aligned d3 value of 103 n 1 th data d9 value of 9 n 1 1 0 th data begin aligned text d9 text value of left frac 9 times n 1 10 right text th data end aligned d9 value of 109 n 1 th data from this formula it is given that the 5th decile is the median since 5 n 1 10 is the data point that represents the halfway point of the distribution deciles in finance and economicsdeciles are used in the investment field to assess the performance of a portfolio or a group of mutual funds the decile rank acts as a comparative number that measures the performance of an asset against similar assets for example say an analyst is evaluating the performance of a set of mutual funds over time a mutual fund that is ranked five on a decile scale of one to 10 means it s in the top 50 by splitting the mutual funds into deciles the analyst can review the best and worst performing mutual funds for a given time period arranged from the smallest to highest average return on investment the government also uses deciles to determine the level of income inequality in the country that is how income is distributed for example if the top 20 wage earners of a country of 50 000 citizens fall in the 10th decile and earn more than 50 of the total income in the country one can conclude that there is a very high degree of income inequality in that country in this case the government can introduce measures to decrease the wage gap such as increasing the income tax of the rich and creating estate taxes to limit how much wealth can be passed on to beneficiaries as an inheritance example of a decilethe table below shows the ungrouped scores out of 100 for 30 exam takers 485255575860616465666972737576788182848788909192939495969799using the information presented in the table the 1st decile can be calculated as let s calculate the 3rd decile 