Compensation survey market data is not a representative source of information in the sense of a representative sampling assuring that inferences and conclusions can safely extend from the sample to the population as a whole.
Salary reports should therefore always be used with care!
We recommend to use salary comparisons in combination with other sources, e.g. multiple compensation surveys, data from labour agreements, an internal analysis of employees' and new hires' pay based on an analytical job evaluation, etc.
The population of a survey (i.e. the participating companies and employees) changes with every issue. Hence vendors are faced with the challenge to maintain a certain level of consistency of their benchmark salaries between the years. To do this, the providers use different approaches to analysing and preparing their salary reports.