Sometimes the information about each and every unit of the population is required. This is possible only through the complete enumeration because the sample will not serve the purpose. Some examples in which the sampling is not allowed are:
To conduct the elections, we need a complete list of the votes. The candidates participating in the election will not accept the results prepared from a sample. With increase in literacy, the people may become statistical minded and they may become willing to accept the results prepared from the sample. In advanced countries the opinion polls are frequently conducted and unofficially the people accept the results of sample survey.
Tax is collected from all the tax payers. A complete list of all the tax payers is required. The telephone, gas and electricity bills are sent to all the consumers. A complete list of the owners of land and property is always prepared to maintain the records. The position of stocks in factories requires complete entries of all the items in the stock.