who have access to official raw data on births and deaths construct their own life tables rather than relying on official ones (Shkolnikov, 1994; Shkolnikov et al., 1994). International agencies that receive data from the NIS countries usually do not evaluate those data beyond checking for basic internal consistency. In short, there is little or no standardization in approach at the present time. If the standard or the approach changes, or if it differs across regions, then comparisons over time or by region will be affected.
In publications such as the United Nations Demographic Yearbook, data from a given country are designated as accurate or as estimates based on the statement of the country that contributed the data, rather than any assessment conducted by United Nations staff. Users sometimes think that because the data are not designated as estimates or of questionable quality, they have been judged accurate as the result of some kind of data quality assessment.
A critical question for any consumer of official statistics from the NIS, especially for the less-developed regions, is how the statisticians have addressed or taken into account known problems in previous data.
Two basic problems with age data affect mortality estimates: age heaping and age exaggeration. Both of these problems are common for populations in less-developed countries, and there is evidence that they create problems with data from the former Soviet Union, especially Central Asia. Garson (1986, 1991) and Bennett and Garson (1983) have shown the implausibility of both the high number of reported centenarians in Soviet censuses and the low reported mortality rates among the elderly.
A common form of age heaping occurs when too many people claim to have an age that ends in a zero, a 5, or an even number, or too many claim to have been born in a year that ends in a zero, a 5, or an even number.8 Although age heaping causes some problems in itself, it can be taken as an indicator of other problems with age data (Ewbank, 1981). Extensive age heaping has been documented in many parts of the world, including Latin America (Nuñez, 1984; Kamps, 1976). It has also been documented for the Central Asian republics by Soviet demographers (Sachuk and Minaeva, 1976) and for Russia in the 1959 census, as well as in death registration for 1958 (Urlanis, 1976). We have found evidence of severe age heaping in the 1990 Census of China for Uighurs and Kazaks, traditionally Moslem peoples who speak a Turkic language and are closely related to Moslem nationalities in former Soviet Central Asia (Anderson and Silver, 1994c). When responding to the 1990 Census of China, 14 percent of male Uighurs in Xinjiang Uighur Autonomous Province claimed to have been born in a year that ended in a zero.
Another problem is age exaggeration, whereby people claim to be older than they actually are, or the age at death of persons who have died is reported as older