T HE measurement of firm size plays a crucial role in applied microeconomics and industrial organization. Firm size has figured prominently in numerous studies of economies of scale in production, advertising, capital market, and cash balances, and in studies of concentration, diversification, profitability, regulation, technological change, and research and development. Even when firm size was not their main concern, many studies often found that size emerged as a robust empirical variable.' All these studies have based their findings on different alternative measures of firm size, often implying that great care in choosing between them is unnecessary since the measures are highly intercorrelated. In a note in this REVIEW, Smyth et al. (hereafter SBP) were the first to recognize that alternative measures of firm size are not interchangeable unless stricter conditions than correlation are met. They have further shown that empirical findings regarding economies of scale are not invariant with the size measure chosen, and that often different conclusions can be reached depending on the particular size measure used. The purpose of this paper is threefold: (I) to offer a general stochastic model that rigorously spells out the conditions for interchangeability among alternative measures of firm size, and of which SBP's deterministic model is a special case; (2) to conduct a statistical test of the interchangeability conditionis using a larger number of size measures, and a far larger sample than the one employed in SBP's empirical test; and (3) to empirically analyze the statistical properties of the most commonly used measures in order to help future investigators in selecting appropriate size measures suitable for their purposes. Section I reviews SBP's work, section II discusses the measurement problem, section III presents our theoretical model, and section IV concludes with some empirical evidence

T HE traditional hypotheses of industry organization relate various aspects of market structure to cross-sectional variation in profitability among industries or firms. It is presumed that association between profitability and structure indicates the existence of excess profits that would be absent under perfect competition. The fundamental causes of excess profits reaped by a whole industry are the existence of entry barriers, and the ability of firms within the industry to coordinate their output-price decisions. On the other hand, varying profitability among firms even within an industry may be due either to the superior bargaining position of the firm within a system of oligopolistic coordination or to superior efficiency in production and distribution. The relationship of structure and profitability, and the attendant interpretations, have been repeatedly examined at the level of ex post rates of return on capital. Such rates are by nature backward-looking since they register the average success of past investments. They do not, therefore, reveal the ability of a firm to retain and extend its excess returns into the future. In contrast to traditional studies this paper seeks to examine the future-oriented implications of market structure. A forward-looking index of profitability is a firm's market value. The basic issue which can be examined in the light of a value-based test of profitability and market structure is this: Does current structural position imply an ability on the part of the firm to maintain excess profits in the future? It must be noted that even if current structural position implies (or is implied by) superior efficiency, the ability of the firm to maintain such advantages into the future implies correspondingly a deficiency in the long-run competitive process since entry would presumably be expected to wipe out such efficiency differentials. It should also be clear that even if the basic question posed were answered in the negative, this would not imply that structural position is unrelated to ex post profits. Thus, the scope of the current work is complementary to traditional studies. The theoretical premises of the hypotheses are laid out in section B. Section C contains a description of specification for statistical tests. Section D presents empirical results and section E summarizes major conclusions

A jobseeker's attitudes towards risk and his perception of the risk inherent in the labor market he is searching have been shown to have a theoretical effect on his expected duration of search, when he is assumed to be searching for jobs in an optimal fashion.' However, no empirical research has adequately tested for these predicted effects.2 This article presents estimates of a reduced-form equation derived from the job search theory3 and tests the following two hypotheses: (1) as the standard deviation of the distribution of potential wage offers increases, an individual's expected duration of unemployment will increase, ceteris pariblis; (2) an individual who is more risk averse than another will have a shorter expected duration of unemployment, ceteris paribbls. The empirical results presented here tend to support both of these hypotheses. Both Kohn and Shavell (1974) and Pissarides (1974) prove, within models of optimal job search, that the more risk averse a job seeker, the lower he will set his minimum acceptable, or reservation, wage. The reservation wage is set to equate the marginal cost of an additional period of search with the expected marginal return from search; any job offer exceeding this wage is accepted and unemployment terminates.4 Determinants of the individual's reservation wage include costs of search, his risk preferences, and his view of the distribution of possible wage offers facing him. As an individual lowers his minimum acceptable wage he will shorten his expected spell of unemployment, given that the distribution of wage offers from which he draws is unchanged. Hence, the more risk averse jobseeker, by lowering his reservation wage, will have to search a shorter period of time, on average, to find an offer acceptable to him. The effect of wage dispersion on duration of unemployment (allowing for adjustment in the reservation wage) cannot be predicted in general from models of job search, despite the belief expressed (from Stigler (1962, p. 236) to Hall (1975, p. 324)) that this effect should be positive. However, when a rectangular wage offer distribution is posited, the intuitively appealing hypothesis (1) can be obtained from a static model of job search (for example, McCall's model (1970)). While the regression specification used in this study to test the two implications presented above was developed in the context of the job search theory, alternative theories could produce these results; hence, the empirical work discussed here is not seen as a test of the search theory.5 Instead, a negative relationship between risk aversion and duration of unemployment could reflect a tendency for individuals to choose occupations and industries with patterns of employment suiting their risk preferences. And a positive association between dispersion in potential wages and duration may

A country's exports are conventionally explained by its export prices relative to competitors' prices and by importing countries' real income. Except for its export prices, the demand for its exports is determined by factors beyond its control. It is thus usually assumed that the country passively responds to the multiplier effect that export demand generates in its domestic economy. This view is common both in macroeconomic theories of short-run income determination and long-run growth of an open economy. However, competition is imperfect in international trade. Apart from barriers set up artificially by importing countries, there are non-price factors in product quality, marketing, and services that make competition imperfect in international markets. Just as sellers can influence their demand curves in domestic markets by advertising, exporters can affect foreign demand through non-price competitive activities, e.g., export promotion. Moreover, imperfect availability of information gives a strong edge to well-established trading connections, which should become firmer as the exporting country expands in scale. In a dynamic world, process and product innovations are continually introduced; old goods are improved in quality and new goods come into existence. A country that leads others in initiating these innovations enjoys a dynamic comparative advantage. Thus, we can make a strong case that non-price competitiveness is significantly associated with an exporting country's growth performances. This argument suggests that domestic growth is an important determinant of the growth potential of a country's industrial exports. A fast-growing country could increase its exports more rapidly than a slow-growing country. While the former enjoys trade surpluses, the latter suffers from trade deficits. The balance of trade could be divergent rather than convergent in the process of growth. The experiences of industrial countries in the two decades preceding 1971 seem to be consistent with this interpretation. We wish to test our hypothesis and to evaluate how far it can account for differences in individual countries' export performances. This article presents such an empirical test by examining export records of major industrial countries over the 1955-1970 period through estimating a cross-country export demand function. Our investigation indicates that domestic factors were a particularly important determinant of export demand. We emphasize that the omission of these factors from the export demand function can make trade projections err and, consequently, lead to wrong policy prescriptions. We introduce export demand and supply functions in section II, examine data and variables in section III, present cross-country estimates of the export demand function in section IV, account for intercountry variations in the conventionally estimated world-income elasticity of export demand in section V, discuss a few econometric problems in section VI, and give concluding remarks in section VII.

F OREIGN private direct investment has a number of economic effects on the capitalreceiving country. Although these have usually been assumed to be beneficial, several recent papers suggest that the issue may be more complex.' While much of the attention to this subject has come from those concerned with developing countries, these issues have applicability in all countries receiving foreign investment. This article examines foreign investment's effect on the quantity of private investment in the capital-receiving country. Many development models simply assume that a dollar of foreign investment produces an equal increase in investment.2 However, microeconomic analysis suggests that the increase in resources will be split between an increase in investment and an increase in consumption.3 Several recent empirical studies provide support for the latter approach.4 In addition to affecting investment in this way, foreign investment can cause an increase in investment beyond the size of the resource inflow through complementary effects. Moreover, to the extent that investment depends on income through an accelerator type of mechanism, changes in expenditure produced by foreign investment will cause still further changes in investment through changes in income. The purpose of this article is to measure the size of foreign investment's effect on investment in Canada. Moreover, the nature of foreign direct investment's impact will be clarified by tracing through its effect on consumption, exports and imports, as well as on investment. Such an approach not only makes possible a better assessment of the desirability of foreign investment, but suggests ways in which policy makers can effect change

TN following the mean-variance analysis developed by Markowitz (1952) and Tobin (1958), Sharpe (1964), Lintner (1965a, b) and Treynor (1961) have developed the theory for determination of asset prices under conditions of uncertainty. The equilibrium asset pricing model, and its implication for measuring ex post performance of individual securities, have been empirically tested by Lintner,1 Jensen (1968, 1972), Miller and Scholes (1972), Douglas (1969), Roll (1969) and others. The empirical results obtained by both Douglas and Lintner deviated from the theory of the model. Moreover, Miller and Scholes have run empirical tests similar to those of Douglas and Lintner and found a significant disparity between the theoretical model and the empirical evidence. They maintain that part of this discrepancy can be explained by possible statistical biases, measurement errors, and consideration of the skewness of the distribution of returns. Black, Jensen, and Scholes (1972) (hereafter B-J-S) confirm the systematic bias. Using monthly data covering a 35 year period, they discovered that, on average, high risk securities earned less than the amount predicted by the model. Similarly, earnings on low risk securities exceeded the amount predicted.2 Although these disparities clearly suggest some systematic empirical bias, we are not examining a possible statistical bias but a mathematical bias stemming from one of the assumptions underlying the capital asset pricing model (CAPM). To be more specific, the model assumes that all investors are single period, expected utility of terminal wealth maximizers. There is no particular restriction on the length of this period as long as it is identical for all investors. Clearly, the length of the true investment horizon affects asset prices under conditions of uncertainty. We claim that the disparities noted above may result from using data calculated for an investment horizon that differs from the true investment horizon. In the various empirical tests, the investment horizon has been selected arbitrarily. For example, Lintner and Miller and Scholes use annual data (i.e., they implicitly assume a one-year horizon), Douglas uses quarterly and annual data; Black, Jensen and Scholes, as well as Friend and Blume (1970), use monthly rates of return in their empirical tests, while Roll uses weekly data. It has been shown elsewhere by Levy (1972) that the Reward to Variability index (developed by Sharpe, 1966) is a function of the investment horizon assumed. Hence, there exists a systematic mathematical bias that is a function of the horizon assumed. The above theoretical findings are related to the theory of pricing capital assets, but deal only with efficient portfolios and not individual stocks. In this paper we illustrate that the assumed horizon plays a crucial role in empirical testing. Any deviation from the true horizon causes a systematic bias in the regression coefficient (i.e., in the security systematic risk). This in turn causes a systematic bias in the performance measures of each security, and hence the deviation between the theoretical model and the empirical evidence. The results of this paper are not limited to the theory of pricing capital assets; they are applicable to any econometric study in which the variables have multiplicative rather than additive properties. In such a case the regression coefficients will have a matheReceived for publication February 27, 1975. Revision accepted for publication March 8, 1976. The authors acknowledge the technical assistance of Moshe Smith and two anonymous referees. The first author has been partially financed by the Maurice Falk Foundation, and the second author has been financed by the Ford Foundation. 1 Lintner's paper Security Prices and Risk: The Theory and a Comparative Analysis of A.T.&T. and Leading Industrials was presented at the Conference on Economics of Regulated Public Utilities, June 24, 1965, Chicago. 2 Miller and Scholes show that the presence of certain biases could have accounted for the Douglas and Lintner findings. BJ-S maintain that the assumption of borrowing at riskless interest rates could have accounted for these deviations

The pseudo data approach to the joint production of petroleum refining and chemicals is described as an alternative that avoids the multicollinearity of time series data and allows a complex technology to be characterized in a statistical price possibility frontier. Intended primarily for long-range analysis, the pseudo data method can be used as a source of elasticity estimate for policy analysis. 19 references.

O UR understanding of the serviceproducing sector of the economy is seriously constrained by the inadequacy of measures of real output for the major service industries. Analyses of industry growth and productivity are only as good as the industry output measures on which they are based; and for many service industries (especially finance, insurance, government administration, health services and education) the real output measures that are generally adopted are poor indeed. In some cases production in the service sector, as measured in the national accounts, is no more than an index of labor input, with the result that the calculation of productivity change is essentially a tautological exercise. In almost all cases economists have had to reconcile themselves to the fact that at least part of the disparity in productivity growth between the service and goods-producing industries is a statistical illusion resulting from the inadequacy of existing data and techniques of measurement.

B. T. McCallum, The Role of Speculation in the Canadian Forward Exchange Market: Some Estimates Assuming Rational Expectations, The Review of Economics and Statistics, Vol. 59, No. 2 (May, 1977), pp. 145-151