1.3 Comparability of statistics

One of the main uses of statistics is to make comparisons, either between different points of time or between different regions. The comparisons may concern

For a comparison to succeed as well as possible, the figures compared must be based on comparable statistics. This means that all the statistics are computed in the same way, i.e. that they are based on the same concepts. It is crucial that the statistician closely adheres to the agreed concept definitions -no attenuating or aggravating circumstances may be taken into account so that the end-user knows exactly what the statistics measure.

Nevertheless, statistical comparisons should be done with care. If there are large differences between the compared regions or point in time it is difficult to find comparable measures.

For example, consumer prices have been systematically monitored since the 1950s. However, it is quite difficult to compare price levels in the 1950s with the present day because consumption habits have changed so considerably. Products that used to be important to the price level in the 1950s have completely lost their significance, and new products have emerged to take their place in people's everyday life.

Comparisons between countries are made difficult by differences in natural conditions, cultures and legislation. A user of international statistics should be careful when drawing conclusions. For example: