The price resulting from a calculation may be regarded as symbolizing (representing) one transaction, or many transactions at once, but the validity of this "price abstraction" all depends on whether the computational procedure and valuation method are accepted. The use of ideal prices for the purpose of accounting, estimation and theorising has become so habitual and ingrained in modern society, that they are frequently confused with the real prices actually realised in trade. Prices may be viewed only as a kind of data, information, or a type of knowledge, or the information available about a money quantity may be equated with the "real thing" (in the
Austrian school of economics, prices are often regarded as data and as information, or as
representing information, although admittedly market actors do not necessarily know all the information which is distilled, summarized and represented in the price numbers). Unfortunately, politicians may not always speak truthfully about trade. The concept of price is often used in a very loose sense to refer to all kinds of transactional possibilities. That can lead to theoretical errors. The notion of "the price of something" is often applied to sums of money denoting various quite different financial categories (e.g. a purchase or sale cost, the amount of a liability, the amount of a compensation, an asset value, an asset yield, an interest rate etc.). For example, an interest rate can be defined as the "price" of borrowing money for a period of time. Here, the concept of price is used in the loose sense of "a cost" or "a compensation." This loose sense means that the distinction between actual prices and ideal prices is lost. In turn, that means that the concept of price then stands for any kind of commercial valuation we care to make. Any activity, thing or transaction has its "price-tag", so to speak. It can be difficult to work out, even for an economist, what a price really means, and price information can be deceptive. A price is not necessarily
transparent, just because it is a market price. This was already known in ancient civilizations. A
Latin expression from Roman times is
caveat emptor which means "let the buyer beware" (for example, when buying a used vehicle). In
contract law, a "caveat emptor" clause is a disclaimer which stipulates that sellers cannot be held responsible for what buyers do not know about their purchase, i.e. it is accepted that there exists
information asymmetry to some or other degree (the purchase may - or may not - include a warranty or legal guarantee which, under specified conditions, gives the buyer his money back). Another Roman expression is
Cui Bono which means "who profits or benefits from it?" - that is, one needs to examine the intended purchase carefully, and identify/weigh what buyers and sellers stand to gain from the deal (what their own interest is). Ideal prices are typically prices that
would apply in trade,
if certain assumed conditions apply (and they may not). Ideal prices are typically not observable, but instead
inferences from observables. Transactions are registered in accounts, the accounting information is aggregated up to compute price data, and this data is in turn used to estimate price trends. In the process of so doing, there is a transition from observable price magnitudes to inferred price magnitudes. At best one could say, that the inferred price magnitudes are based on observable price magnitudes, but the link between them can be rather tenuous, since specific valuation assumptions may be introduced, so that the calculation procedure goes far beyond a simple arithmetical aggregation. Purely theoretical prices used for analytical purposes, estimation or calculating alternative scenario's may have no correlate in the real world. How exactly they relate to the real world might be unknown. The knowledge of prices may have an effect influencing trading possibilities, which in turn changes the knowledge of prices. Consequently, such knowledge is often kept confidential or is a business secret (see also
information security and
sociological aspects of secrecy). A price system is therefore not necessarily transparent at all, quite apart from disputes over how a price is calculated, estimated or derived. ==Are prices exact?==