The unemployment rate measures:
the number of people unemployed divided by the number of people employed.
unemployed workers as a percentage of the labor force.
unemployed workers as a percentage of the population age over-sixteen.
unemployed workers as a percentage of the population.

unemployed workers as a percentage of the labor force  

Explanation:

The level of unemployment refers to  the proportion of the unemployed population, measured as a statistic. This is a stagnating predictor, which means this normally grows or drops in the face of shifting economic circumstances instead of predicting them.

The rate of joblessness should be projected to rise whenever the country is in bad condition and opportunities are limited. If the economy expands at a steady pace, and workers are fairly stable, it could be predicted to decline.                            

answer; standardization;