National Minimum Wage

Appendix 4
Main Data Sources
Introduction
1 In this appendix we outline the main data sources used in our analyses and look at any
significant changes that have been made since our 2011 Report. There are three main
sources of data that we use in this report to measure earnings: the Annual Survey of Hours
and Earnings (ASHE), Average Weekly Earnings (AWE), and the Labour Force Survey (LFS).
We also consider the measures of earnings from the National Accounts. These are all
published by the Office for National Statistics (ONS). There are two main sources of
employment information: the LFS and the ONS employee jobs series. The LFS captures the
number of people in employment, whereas the employee jobs series measures the number
of jobs in the economy. This is an important distinction as a person can have more than one
job.
2 ONS has revised the Standard Occupational Classification (SOC) that defines occupations.
The new classification (SOC 2010) is replacing the previously used SOC 2000 in ONS
outputs, but it is not possible to make direct comparisons between data on the old and new
classifications. Our definitions of low-paying occupations are based on SOC 2000, and we
have explained the implications of this change in the following sections.
3 In addition to labour market data, we also look at a variety of macroeconomic data. The final
section of this appendix outlines the two main macroeconomic datasets that we use,
measuring inflation and gross domestic product (GDP), and summarises the revisions that
ONS have recently made to the GDP figures.
Annual Survey of Hours and Earnings
4 ASHE is the main source of structural earnings data in the UK and is regarded by ONS as the
best source of earnings information. It provides information on the levels, distribution and
make-up of earnings, as well as on hours, gender, age, geography, occupation and industry.
It is a survey of employees completed by employers and relates to a reference period in April
each year. Results are based on a 1 per cent sample of employees in Pay-As-You-Earn income
tax schemes obtained from HM Revenue & Customs (HMRC). The self-employed are
excluded. We carry out our own analysis of earnings from ASHE whereby those employees
not on an adult rate of pay are included in the dataset (they are excluded from ONS ASHE
earnings estimates). This means that our earnings estimates will be different from those
published by ONS.
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