What Decile is
Deciles are a type of quantile that divides data into 10 groups of equal size, each group containing 10% of the observations.
The steps for calculating deciles are as follows:
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Organize the data into ascending order.
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Count the number of observations in the data set.
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Divide the number of observations by 10 to determine the size of each decile group.
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Determine the lower boundaries of each decile group. The lower boundary of the first decile group is the smallest value in the data set. The lower boundary of the second decile group is the sum of the smallest value and the next largest value. This process continues until the lower boundary of the tenth decile group is determined.
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Calculate the decile values. The decile value for each decile group is the average of the lower boundary and the upper boundary of the group.
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Interpret the deciles. The first decile is the smallest 10% of the data set. The second decile is the next 10%, and so on.
Examples
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Decile analysis can be used to compare the performance of different stocks in the same sector.
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A decile analysis can be used to compare the performance of different countries in terms of economic growth.
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Deciles can be used to compare the performance of different schools in terms of student achievement.
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Deciles can be used to compare the performance of different hospitals in terms of quality of care.
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Deciles can be used to compare the performance of different companies in terms of customer satisfaction.