The data include bonuses, holiday pay and pay arrears. No adjustment is made for part-time workers. All branches of economic activity, except the armed forces. Seasonally adjusted indices are also produced together with a headline rate of growth which comprises the percentage change in the three-month average value of the seasonally adjusted index compared with the same period one year earlier.
Some further data excluding bonus are also available.
For weekly staff, data for the last week of the month is generally sought, except where it is unrepresentative, for example as a result of holidays. For monthly paid employees, data for the whole month is collected. The majority of data are collected through completion of a standard MWSS survey questionnaire, but some organizations provide composite responses on behalf of their members. The AEI uses weights based on employment numbers. This 'chain linking' ensures that the index takes advantage of the most recent data on employment numbers, and therefore reflects changes in the industrial composition of employment.