1. Sources of demographic data Population census Sample Surveys Population registers Other sources The balancing equation

2. 1. Population census  The modern population census may be defined as the process of collecting, compiling, evaluating, analyzing and publishing demographic, social and economic data about the entire population of a well defined territory at a specified time.

3. Planning and execution of the census  During the planning stage of a population census the persons responsible have to:  Decide on the system of enumeration to be used;  Fix the date of the census and set out the pre census programme;  Decide on the type and content of the questionnaire;  Test all forms and procedures including final pre-test;  Prepare detailed maps and list all dwellings;  Recruit and train the field staff;  Plan and programme for processing of the data;  Inform the public and obtain their co-operation.

4. 2. Sample Surveys  Another major source of demographic data is the sample survey. Some example of its use are:  To collect vital statistics where the official registration system is inadequate or non-existent, as is the case in most developing countries.  To collect supplementary demographic and other data where it is not feasible to collect the same from the population census (e.g. public opinion polls; surveys on topics such as labor force etc.)  To test accuracy of additional sources of demographic data (e.g. census pre testing of questionnaire and census post- enumeration quality check in a sample of census blocks).

5. Cont…  To conduct a sample census (e.g. collecting data from only 10 per cent of the population; collecting age and sex data for the whole population but socio- economic data for only a sample of the population; processing only a part of the information collected to save time and money and present a wider range of tabulation).

6. 3. Population registers  In those countries which possess a system of continuous registration, it is possible to maintain a separate card for each individual from the time of his birth (or immigration) to his death (or emigration) and to continually update the record by recording such additional registration data as marriage, divorce, birth of children, etc. these are called population registers and are maintained in most of the countries.

7. Advantages of population registers  The advantages of the system include  the completeness of coverage,  accuracy,  contact with individuals if required and  possibility of drawing specific samples of population.

8. Disadvantages of population registers  Disadvantages are:  High cost to set up and maintain;  The need for a high cultural and educational level.

9. 4. Other sources of demographic data  Apart from the population census, the registration of vital events and demographic sample surveys, there are many other sources of demographic data of somewhat lesser importance.  These are usually records held by various government and semi-government departments which are useful in demographic analysis.  Data on registrations for military service, employment statistics, social service records about pensions and child endowment, primary vaccination statistics, the records of hospitals and educational institutions, electoral rolls, taxation records etc.

10. The balancing equation