Problems OF Using Data Sources 1/Contrary to Popular Opinion,Census Statistics are Subject to many errors and limitations.In remote rural areas infants who die before registration may not be enumerated.It has been estimated, for example,that even in the USA almost 2 Per cent OF births still escape registration.Some of these result from breaks in Sequence or the lack of a regular sequence in the census years in the UK, for example, there was no census in 1941, while in France the rhythm of a supposedly Five-yearly census interval was carried out in 1946, 1954,1962,1968 and 1975.National registers , while generally more reliable, also Suffer from inaccuracies.2/For the geographer working on census Statistics there are many problems.Russia , for example, has held a Census on five occasions only , in 1879, 1926, 1939, 1959 and 1970.These result from Omissions and double entries.Other states make no attempt at a regular census interval.In China , the first census was not held until as last as 1953, wheneither as a result or political motives .