text: Statistical Office of the European Community or any other international body; (c) The two sets of prices would be combined in a single table, and the "country-product-dummy" (CPD) method could be used to estimate the price missing in the table; (d) The resulting PPPs then have the advantage of being the same for any pair of countries within a group, but regional specificities are also introduced. (The latter capability might be of particylar interest for separate comparisons of countries with similar defence structures, such as the nuclear Powers.) D. Problems specific to military expenditures 43. There are a number of problems which are particularly important with regard to the comparison of military expenditures, although they are not entirely unique. These problems include: (a) the secrecy surrounding military information; (b) the difficulty in determining prices; (c) the high degree of differentiation with regard to military equipment and construction; and (d) the lack of market prices. (a) It is a well established fact that at present a substantial part of military information, especially with regard to weapons and weapon SyStemS, is surrounded by secrecy in various degrees, depending on the country. Although it is possible to use various means of intelligence to estimate a country's physical forces in terms of numbers of ships or tanks, it is much more difficult to make financial estimates on the basis of such information. Often the cost of equipment is not made known, whether it is imported or manufactured domestically. On the one hand, Governments do not wish to indicate the cost of their purchases. Arms contracts are quite often linked to economic and/or political deals in which the real. cost of arms is at times difficult or even impossible to establish by the participating Governments themselves. On the other hand, where domestically 
analysis: The text discusses the challenges and methods of comparing military expenditures between countries, which suggests a strong connection to international trade and economic development. The focus on prices, market values, and the difficulties in estimating costs also points towards an economic context.