It is just over two years since the first Inside Statistics appeared. On the occasion of the 100th column, it seems appropriate to review the sometimes turbulent changes in official statistics charted and presented in the column.
The error in estimating the rental component of consumer price indices was dealt with extensively in earlier columns. Stats SA's investigation into the cause of this error, and the steps taken to rectify weaknesses in collection of price indices, were the subject of a number of articles.
The work of a consortium of international statistical specialists convened to assist Stats SA in assessing its economic outputs was detailed over a period of time.
Later on, pilots to test direct collection methods for prices, rather than postal surveys, were also discussed and reported on, while the massive change in the register used for drawing samples for economic surveys was an ongoing theme.
The construction of a new business register, based on company registration records of the SA Revenue Service, was the single largest element in the revision of economic measurement.
This enabled more extensive coverage of economic activity in all sectors, and underpins the upward revisions undertaken in a number of the economic series.
One consequence of this improved measurement was the upward revision of gross domestic product (GDP). The different factors involved in the November 2004 release of GDP data (revision, rebasing, benchmarking, and improvements in measurement) have been common themes.
A related theme involved resistance to change in economics statistics, with the arguments of those prioritising consistency and stability being weighed against those committed to improvements in quality and coverage.
The use and abuse of statistics, particularly when data is mobilised in support of vested or specific interests, formed a constant backdrop to the discussion of economic measurement.
Revision and change is never easy, and the redevelopment of Stats SA's economic series is no exception.
Stats SA has, in the past two years, been criticised for revisions made as a result of improved data quality, and a number of editions of Inside Statistics drew attention to what Len Cook, respected national statistician and head of the British Office of National Statistics, has referred to as the "expected and inevitable" nature of statistical revision.
While often focusing on economic measurement, Inside Statistics has discussed many of the other elements in the statistical cycle. A series discussed each of the major moments in a population census, drawing examples from South Africa's 2001 census.
Different ways of collecting statistics - through censuses, surveys, administrative records and registers - have been evaluated.
Stats SA's involvement in structures and systems for the development and co-ordination of statistics have been reported on, with South Africa's evolving national statistics system receiving regular attention, together with the UN Statistical Commission, Southern African Development Community, other African statistics bodies, and the Partners for the Development of Statistics in the 21st Century (Paris21) as part of the UN system of statistics.
This column has chronicled Stats SA's development of web-based technologies for online data access and mapping functionality; the release of digital and interactive products; and set out details of the project to build a warehouse for storage and retrieval of statistical data.
A guiding principle in compiling Inside Statistics has been transparency. Difficulties and risks have been openly discussed, and the almost-inevitable errors which accompany complex processes of statistical change identified, acknowledged and debated.
Official statistics has come a long way since the first column appeared. The economy is being measured more accurately, on the basis of better samples drawn from a new business register.
Errors in this set of processes cannot be excluded, nor will they be hidden or denied. There may be future revisions, as the business register is progressively expanded.
Inside Statistics looks forward to charting these sometimes turbulent, but always interesting, waters together with its readers and users of statistics.
Pali Lehohla is South Africa's statistician-general and head of Statistics SA. For more information on Stats SA and its outputs visit www.statssa.gov.