Inflation,

change in the quality of care is primarily due to the increased demand caused by the growth of private and public insurance. The paper presents an analytic model of the hospital industry in which quality affects the demand for hospital services and in which the purchase of private insurance is endogenous. Estimates of key equations of the model based on a cross-section of time series for the individual states for the years 1958 through 1973 are presented. The price adjustment process and dynamic multipliers are discussed. THE COST OF A DAY of hospital care in the United States has increased 600 per cent in the past twenty years, an annual rate of more than 9 per cent. During the

[Although the theory of taxation and portfolio choice has been extensively developed, the current paper begins the econometric study of this subject. The research analyzes the composition of portfolios of 1,799 households in a sample in which high income individuals are greatly overrepresented. The results show that the personal income tax has a very powerful effect on individuals' demands for portfolio assets after adjusting for the effects of net worth, age, sex, and the ratio of human to nonhuman capital.]

[The problem of collinearity suggests the search for an alternative to ordinary least squares which, although biased, might reduce the mean square error of the coefficient of interest. Two types of estimators are examined, and the corresponding mean square error loss functions are calculated.]

[This paper presents formulae for the standard error of forecast of a single equation and the covariance matrix of forecasts of a complete system of equations that are appropriate when the exogenous variables in the forecast period are stochastic. The problems of defining forecast intervals and multidimensional forecast regions are also discussed.]

This paper develops an economic theory of replacement investment that can provide a basis for specifying an econometric model of investment behavior. The long-run and short-run effects of changes in the interest rate and in tax laws are examined. The paper also investigates several reasons why the common assumption of a technologically constant rate of replacement is incorrect even as an asymptotic limit. LARGE VARIATIONS in capital spending continue to motivate econometric studies of investment behavior. The past decade has seen the development of attempts to model net investment as the adjustment of the capital stock to a desirable level. Building on earlier work by Lutz [35], Haavelmo [21], and others, Jorgenson and his collaborators (e.g. [24, 28, 31, and 33]) have provided an operational model of net capital accumulation that relates desired capital to the cost of capital services. Although serious objections have been raised about the specification of the optimal capital stock (including [5, 9, 13, and 15]) and about the arbitrary nature of the adjustment dynamics [37], it is likely that some form of this general model will continue to provide a framework for future investment studies. In contrast to these developments of a theory of capital expansion, replacement investment continues to be analyzed in terms of a non-economic model of technical necessity. Jorgenson and others have adopted the simplifying assumption that replacement investment is a constant proportion of the capital stock.2 This assumption has been challenged and contrary evidence has been offered by Feldstein and Foot [14] and Eisner [10]. The purpose of the current paper is to examine several aspects of a theory of replacement investment. We hope not only to show that a model with a constant replacement rate is implausible and unsatisfactory but also to provide a basis for better empirical work in the future. The magnitude of replacement investment (the annual rate of replacement investment generally exceeds expansion investment) makes this issue a matter of substantial importance.

Charitable contributions are an important source of basic finance for a wide variety of private nonprofit organizations that perform quasi-public functions. The tax treatment of charitable contributions substantially influences the volume and distribution of these gifts. The current study presents new estimates of the price and income elasticities of charitable giving. The parameter estimates are then used with the United States Treasury Tax File to simulate the effects of several possible alternatives to the current tax treatment of charitable giving. INDIVIDUAL CHARITABLE CONTRIBUTIONS are an important source of basic finance for a wide variety of private nonprofit organizations. Higher education, research, health care, the visual and performing arts, welfare services, and community and religious activities rely heavily on the voluntary institution. In 1970, American families contributed more than $17 billion for their support. The volume and distribution of charitable gifts is influenced by the personal income tax treatment of charitable contributions. There are today a number of widely discussed proposals for changing these rules. The appropriate tax treatment of such gifts involves a complex series of economic issues. Critical to a resolution of these issues is an understanding of the likely quantitative effects of alternative tax rules: the effects on the total volume of charitable gifts and its distribution among the different types of donees; the effects on the distribution of tax burdens