Responsible use of statistics inevitably occurs in tandem with misuse and distortion. On occasion, such misuse is linked to attacks on the integrity of the producers and disseminators of data.
An official statistics agency is often required to draw attention to the erroneous use of statistics. This function is enshrined in principle 4 of the UN Fundamental Principles of Official Statistics.
Such misuse occurred when a well-known non-governmental organisation (NGO) recently accused Statistics SA of releasing the latest data on mortality in a way designed to "cover up" the impact of the data.
This was a strange attack, because the report was announced and released in the same way as all Stats SA publications, and published on the department's central dissemination tool (the Stats SA website). Rather than hiding the data on mortality, I made special mention of the report's imminent release when interviewed on national television on the morning of the release date.
Notwithstanding this, the NGO chose to repeat the allegation just as Stats SA was finalising arrangement for a symposium on adult mortality, based on the report allegedly hidden. This symposium was held yesterday and included participants from the department of health, the Medical Research Council and many others. The workshop was carefully structured to explain the findings of the mortality report, and provided an opportunity for questions, criticism and discussion.
One of the key findings of the report is that between 1997 and 2004, death rates rose for virtually every age and sex group for persons between the ages of 15 and 64. The most distinctive aspect of mortality change across the seven-year period was the large increase in death rates of women aged between 20 and 39, for whom the rate more than tripled, while death rates more than doubled for men aged 30 to 44.
This means that the traditional female survival advantage narrowed, and, indeed, for those aged 20 to 34 it reversed. For women between 15 and 40, survival rates fell from 91 percent in 1997 to 69 percent in 2004.
The implications of this would have been intensively considered at yesterday's symposium, showing up the NGO's attack on Stats SA for what it was - a selective, ill-informed misuse of the statistical process.
Both responsible and less responsible use of statistics are also apparent for economic data. Measurement of economic activity is a complex process. It can be done in various ways through different surveys, each with different methodologies, survey instruments, purposes, levels of detail and frequencies.
Most analysts of the economy are familiar with the monthly and quarterly releases that Stats SA produces on sectors such as manufacturing production, wholesale and retail trade, mining, the motor trade and electricity generated. In addition, a range of price indices track changes in producer and consumer prices.
The headline inflation numbers for the consumer price index (CPI) and CPIX, or CPI excluding mortgage costs, in particular, always attract considerable attention each month, as consumers experience their impact through changes in monetary policy, interest rates and other macroeconomic mechanisms used to regulate the economy.
Gross domestic product (GDP) is another macroeconomic indicator that attracts attention each quarter. It measures whether the economy has grown or shrunk, in what sectors and at what rate.
Interpreting these numbers can be confusing, given the range of indicators released. Each indicator has different purposes and carries specific limitations on use, and the most analytical benefit is gained through viewing each number in the context of related statistics.
A good example involves GDP estimates for the first quarter of this year, which were released on May 30. These reported, as a headline number, that the economy grew at a pace of 4.2 percent for the quarter, on an annualised and seasonally adjusted basis, compared with the fourth quarter of 2005.
Some commentators viewed this as disappointing. Others viewed the same data from a slightly different perspective, and found the estimate for growth in the non-agricultural economy (4.7 percent) a more positive indication. From another perspective, growth in the non-primary sector was reported at 5.3 percent.
Next Tuesday Stats SA will release the preliminary GDP estimates for the second quarter. These will integrate many of the monthly statistics published recently, providing a coherent and comprehensive picture of the economy. The data will report on the performance of the economy for the first half, giving a platform to evaluate the effect of macroeconomic factors such as exchange rates, interest rates, inflation and the oil price. Some analysts will also use the data to forecast economic prospects for the rest of the year.
Responsible users of statistics are not selective when using data to make decisions. They consider all relevant factors and use as many different data sets as possible, evaluating them for comparability, quality and general fitness for use. The same criteria apply when using statistics to form opinions, both on the data and on the credibility of producers and disseminators of statistics.