This study explores the impact of non-constant returns to scale and imperfectly competitive product markets on the empirical performance of the q-model of investment. We present an econometric specification linking the unobserved shadow price of capital to financial market data when returns-to-scale are not necessarily constant and product markets are not necessarily competitive. Furthermore, unlike most Q-studies, we work within a discrete-time framework, and give explicit attention to the relations between inventories, sales, and production. Our new specification allows us to recover parameters characterizing returns-to-scale, product market, and adjustment cost elasticities. Estimates are reported for 12 mature industries in the United States drawn from VALUELINE.

The focus of this article is the comparison of the relative influence of different determinants of investment (demand, the relative price of capital and labour, and profit) for five large European countries and the United States. The investment equations are derived from production functions, either putty-putty or putty-clay, in the context of a disequilibrium model. The comparison of annual and quarterly estimates (after aggregation in a equivalent annual model) improves the evaluation of the precision of the parameter estimates.

In all these countries, in accordance with the accelerator effect, demand is the dominant influence in the short term, fading away in the medium term. In contrast, profit is not a predominant influence except in the medium term. Its role thus seems to result from the effect of expectations on investment profitability rather than from short run self-financing constraints. With respect to factor substitution, the analysis confirms that this is only weakly linked to changes in the relative price of capital and labour.

In this paper we estimate an investment demand function derived from a standard adjustment costs framework. We also suppose that the speed of adjustment depends on the capacity of the firms to finance their investment projects with their own generated resources. The model is estimated for a sample of 140 firms and 4 years (1978-81).

Using the consistent within-groups estimator, the main results are : 1) expected output appears as the most important determinant of investment ; 2) profits affect investment in the long-run only through the adjustment cost channel ; 3) relative factor prices are not significant, reflecting a very slow substitution between labour and capital in spanish industry.

A la suite du premier choc pétrolier, une controverse est née sur les liens entre capital et énergie. Les études sur séries chronologiques montrent, en général, que ces facteurs sont complémentaires alors que les études sur données spatio-temporelles exhibent des substituabilités. Il est cependant très difficile de comparer directement ces résultats, les données utilisées n’étant pas de même nature. Ce travail tente d’apporter un éclairage nouveau sur la question en éliminant la cause à priori la plus suspecte des divergences : les modes de construction des données. Nous avons construit une banque homogène pour les sept grands pays de l’OCDE sur la période 1960-1984 et estimé des fonctions de coût translog KLE et KLEF pour chaque pays et pour l’ensemble.