---
title: "Decile"
chunk: 1/1
source: "https://en.wikipedia.org/wiki/Decile"
category: "reference"
tags: "science, encyclopedia"
date_saved: "2026-05-05T12:22:20.766128+00:00"
instance: "kb-cron"
---

In descriptive statistics, a decile is any of the nine values that divide the sorted data into ten equal parts, so that each part represents 1/10 of the sample or population. A decile is one possible form of a quantile; others include the quartile and percentile. A decile rank arranges the data in order from lowest to highest and is done on a scale of one to ten where each successive number corresponds to an increase of 10 percentage points.


== Decile mean ==
A moderately robust measure of central tendency, known as the decile mean, can be computed by making use of a sample's deciles 
  
    
      
        
          D
          
            1
          
        
      
    
    {\displaystyle D_{1}}
  
 to 
  
    
      
        
          D
          
            9
          
        
      
    
    {\displaystyle D_{9}}
  
 (
  
    
      
        
          D
          
            1
          
        
      
    
    {\displaystyle D_{1}}
  
 = 10th percentile, 
  
    
      
        
          D
          
            2
          
        
      
    
    {\displaystyle D_{2}}
  
 = 20th percentile and so on). It is calculated as follows:

  
    
      
        D
        M
        =
        
          
            
              
                ∑
                
                  i
                  =
                  1
                
                
                  9
                
              
              
                D
                
                  i
                
              
            
            9
          
        
      
    
    {\displaystyle DM={\frac {\sum _{i=1}^{9}D_{i}}{9}}}
  

Apart from serving as an alternative for the mean and the truncated mean, it also forms the basis for robust measures of skewness and kurtosis, and even a normality test.


== See also ==
Summary statistics
Socio-economic decile (for New Zealand schools)


== References ==