PRODUCTION, CENSUS OF. In many countries no general survey of production is available. In countries mainly devoted to agriculture, the ascertainment of the distribution of the cultivated area, and of the quantities of the leading crops and the numbers of livestock maintained, gives information of the greatest importance. Where the extraction of minerals is impor tant, the quantities of such minerals produced are a necessary ele ment in the survey of the country's industrial resources. In various countries in which manufacture has reached a considerable degree of importance, periodic returns of the output of various leading products of the manufacturing industries are added to the records of agricultural and mineral products obtained. These surveys are, however, not merely incomplete in that they fail to cover the pro ductive activities of the country, but they also fail to furnish a satisfactory measure of the results of that activity. For that purpose a census not of products but of production is needed. For the extractive industries the record of products serves to measure production reasonably well, since the value of the prod ucts of other industries used up in the processes essential to the extraction of new products is, in general, comparatively small.
Even in the instance of field crops, a sound estimate of the "production" of agriculture would need, indeed, a deduction from the gross total of crops harvested not only of the seed which has been required to produce those crops, but also of the equivalent of manures used and of the requirements for the placement of tools and equipment so as to maintain the stock of such tools, etc., undiminished. In dealing with animal products, allowances must, in like manner, be made for food consumed in the maintenance of the animals and for other supplies used up in the business of stock rearing, so far as these goods are ob tained beyond the limits of the agricultural industries.
The distinction between a census of products and a census of production has special importance in reference to many manu facturing industries. Effective comparison of different in dustries, and of different divisions of the same industry, cannot be made on the basis of the aggregate value of the products of the industries compared. There are two important reasons for this. On the one hand, if industries were otherwise similar in character, but made use of different materials, they would yield aggregates of products, the value of which would be higher or lower according to the values of these different materials. Mate rials costing £50,000 might be worked up into products worth Lioo,000, and precisely similar operations on materials costing £75,000 might yield products worth £125,000. Measured by the
value of products, the second industry appears to have a yield of 25% greater than the first, while the actual increments in value of materials used were the same in both cases.
On the other hand, the same materials may be advanced from stage to stage in manufacture in different establishments, and the products of the series of establishments will show values grad ually increasing, the material of each being the product of the preceding. It would not be a sound conclusion from such a record that the productive importance of the successive establishments was in the order of the processes, and that the increasing values of the goods from stage to stage reflected the importance of the productive services of the series of establishments. In comparing establishments making use of different materials and conducting processes of manufacture dissimilar in character, as in the two types of cases dealt with above, no true comparison of the value of the productive contribution of each can be expected to result from a simple comparison of the values of their products.
A census of production must, accordingly, be something more than an enumeration of the products of the various establish ments and industries surveyed and a record of their values. The products of other establishments or industries which have been used up in the productive processes surveyed must be ascer tained if a true measure of the production carried on is to be secured. In strictness the effects of wear and tear, so far as not made good by the staff maintained within the establishment for that purpose, and also the effects of obsolescence on the plant and buildings, should be evaluated and included in the deduction from the value of the gross output needed in order to arrive at the value of the contribution made to production. In practice al lowances for depreciation cannot be estimated with a precision approximating to that attainable with reference to cost of mate rials, and adjustments in respect of the consequent overestimate of the production have to be made by some means other than the simple aggregation of the depreciation suffered by each estab lishment. The result of deducting the value of materials used from the value of the products resulting from work on them is designated "net output" in the reports on the Census of Pro duction in the United Kingdom and is dealt with under the title "value added in manufacture" in the reports on the Census of Manufactures in the United States.