The median divides the earnings distribution into two equal parts: one-half of the cases falling below the median earnings and one-half above the median. Median earnings is restricted to individuals 16 years old and over and is computed on the basis of a standard distribution (see the "Standard Distributions" section under "Derived Measures"). Median earnings figures are calculated using linear interpolation if the width of the interval containing the estimate is $2,500 or less. If the width of the interval containing the estimate is greater than $2,500, Pareto interpolation is used. (For more information on medians and interpolation, see Derived Measures.)

The data on sex, which was asked of all people, were derived from answers to long-form questionnaire Item 3 and short-form questionnaire Item 5. Individuals were asked to mark either "male" or "female" to indicate their sex. For most cases in which sex was not reported, it was determined from the persons given (i.e., first) name and household relationship. Otherwise, sex was imputed according to the relationship to the householder and the age of the person. (For more information on imputation, see "Accuracy of the Data.")