does anyone know what the formula is for quintile ratio?

Answer 1

Quintiles divide the data into five equal pieces. The upper quintile is this same as the 80th percentile. The lower quintile is the same as the 20th percentile. In a lot of social studies research, the quintile ratio is sometimes used to look at the upper 20% of the population as compared to the lower 20% of the population.

Suppose, for example, the upper quintile for household income was $100,000. (20% of the population has a household income of $100,000 or higher.) Suppose the lower quintile in household income is $20,000. (20% of the population has a household income of $20,000 or less.) Then the quintile ratio would be 100,000 / 20,000 or 5.

Social scientists sometimes compare the quintile ratio of household income in developing countries to industrialized countries, etc.

Answer 2

Quintile means one-fifth, 1/5, or 20%. Just as a population can be divided into 4 quartiles, it can be divided into 5 quintiles.