Weighted average. Add a horizontal line to the number and mathematically represent it as a weighted average. Weighted average is to multiply each value by the corresponding weight, then add up to get the total value, and then divide it by the total number of units. The average value depends not only on the tag value (variable value) of each unit in the population, but also on the frequency of each tag value. Because the frequency of each sign value plays a role in measuring its influence in the average, it is called weight.