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Mean, median or quartiles?
Statistics Norway now presents figures for mean, median, upper and lower quartiles of all wage variables in Statbank.
Average wages have traditionally been the most common measure to use when comparing wages between different groups, such as various occupations, in the labour market. However, the average says little about the variation in the distribution, and it can provide useful information to supplement the information median and quartiles.
Average earnings (arithmetic mean) are simply calculated by summing up all earnings and dividing them by the number of observations in the group.
The median earnings are found by arranging all earnings in ascending order. The median is the earnings in the middle of the distribution. In the wage statistics, the average is often higher than the median. This is because the upper earnings may be very high while the lower earnings are limited by for example zero, minimum wage tariffs or similar. Some observations with very high salaries will affect the average, but not the median. It is often the case that a large percentage of observations in a group have relatively equal wages and the median is among them.
Upper and lower quartile
The upper and lower quartile values can be found in the same way as the median value, by sorting the material sequentially. The upper and lower quartiles are the values that are the limit for the upper quarter and lower quarter in the material respectively. The quartiles, often in combination with median or average, say something about the distribution of earnings within a group.