In Pakistan, like many other developing countries of the world, age distributions availabe from the decennial population censuses and sample surveys have shown substantial distortions and irregularities [2; 3; 4; 6, pp.64-75; 9, pp.638-658; 13; 14, pp.64-95]. Some of these distortions could be real and may have been the result of events such as the Bengal famine of 1943 and the post-Independence migration between India and Pakistan. Others could be due to the coverage and response problems encountered in the collection of age data. Among the coverage and response problems, two are of most importance: underenumeration of females and erroneous age-reporting. In countries like Pakistan, which have low literacy rates (19.2 per cent literates according to the 1961 Census of Pakistan), most of the people do not know their correct ages. As a result they tend to report their ages either in round numbers or instead ask the enumerators to write down whatever age they think proper. This pheno¬menon of reporting ages in round numbers is usually called “digital pre¬ference”. As a result of this the single-year age distributions show distinct peaks and troughs at ages ending with certain digits.