Definition of quartile in US English:



  • 1Each of four equal groups into which a population can be divided according to the distribution of values of a particular variable.

    • ‘The initial categories were created by stratifying lesions into quartiles according to size.’
    • ‘The resulting distributions for men and women were divided into quartiles.’
    • ‘Children in the upper quartile of the blood-lead-concentration distribution donated another blood sample in February 1993.’
    • ‘White women were older, smoked more, and were less likely to have dietary calcium intakes in the lowest quartile of distribution than black and Hispanic women.’
    • ‘The school is one of several elementary schools within a district that is in the bottom quartile when fourth grade standardized test scores and passage rates are compared throughout the state.’
    1. 1.1 Each of the three values of the random variable that divide a population into four groups.
      • ‘Every measurement was first divided by its plate's quartile and then multiplied by the average quartile of the respective experiment.’
      • ‘Disparities in college enrollment by family income quartiles are almost as large today as they were thirty years ago.’
      • ‘We calculate medians and quartiles of the age at leaving home by sex and race, using a fitted curve derived from a logit regression model.’
      • ‘Here we would like to estimate the quartiles of the distribution of age at leaving home, within categories of covariates.’
      • ‘Simple quartiles cannot be defined in interval variables unless their boundaries chance to fall at interval boundaries.’


Late 19th century: from medieval Latin quartilis, from Latin quartus ‘fourth’.