intersectoral externalities and indeterminacy abstract we consider a two sector economy with positive intersectoral external effects and nonincreasing social returns we show that if the discount factor is close to 1 then local indeterminacy may be obtained with mild market imperfections moreover with additional conditions when is made smaller the steady state becomes totally unstable and quasi periodic cycles along which equilibrium paths are indeterminate may appear through a hopf bifurcation this will be proved even if the investment good is capital intensive at the private level while this condition guarantees local determinacy in the sector specific case journal of economic literature classification numbers c62 e32 o41

customer and retailer rebates under risk aversion abstract in a supply chain setting we analyze a manufacturer s customer and retailer rebates which are sales incentives offered to the end buyers and retailers respectively the performance of both rebates is influenced by the retailer s objective and response to the promotion due to his intermediary position in the channel earlier studies investigating rebates in distribution channels have traditionally assumed that the retailer is risk neutral with the objective of maximizing expected profits in our paper we consider a risk averse retailer we formally model risk aversion by adopting the conditional value at risk cvar decision criterion using a stochastic and effective price dependent demand we analyze the manufacturer s rebate amount decisions and the retailer s joint inventory and pricing decisions in a game theoretical framework we provide several structural properties of the objective functions and show monotonicity of the retailer s decisions in the degree of risk aversion for the case of retailer rebates we characterize the unique equilibrium and for the case of customer rebates we prove the existence of an equilibrium using numerical examples we provide further insights on the impact of risk aversion for example given an exogenous wholesale price we observe a threshold value on the retailer s risk aversion parameter below above which the manufacturer is better off with retailer rebates customer rebates implying that the manufacturer s preferred rebate type can be different depending on whether the retailer is risk neutral or sufficiently risk averse

impact of loss aversion on the newsvendor game with product substitution abstract this paper studies a newsvendor game in which two substitutable products are sold by two different retailers newsvendors with loss averse preferences each loss averse retailer facing stochastic customer demand and deterministic substitution rate will make an order quantity decision to maximize his expected utility since product substitution causes two retailers to make decisions in a competitive environment game theory is used to find the retailers optimal order quantities it is shown that under certain conditions there exists a unique nash equilibrium in the newsvendor game under a symmetry assumption each retailer s equilibrium order quantity is decreasing in the loss aversion coefficient and increasing in the substitution rate further if the effect of loss aversion on the order quantity is strong enough to dominate the effect of competition the total inventory level of a decentralized supply chain will be lower than that of a centralized supply chain numerical experiments are conducted to illustrate our results

pricing and the news vendor problem a review with extensions in the newsvendor problem a decision maker facing random demand for a perishable product decides how much of it to stock for a single selling period this simple problem with its intuitively appealing solution is a crucial building block of stochastic inventory theory which comprises a vast literature focusing on operational efficiency typically in this literature market parameters such as demand and selling price are exogenous however incorporating these factors into the mode l can provide an excellent vehicle for examining how operational problems interact with marketing issues to influence decision making at the firm level in this paper we examine an extension of the newsvendor problem in which stocking quantity and selling price are set simultaneously we provide a comprehensive review that synthesizes existing results for the single period problem and develop additional results to enrich the existing knowledge base we also review and develop insight into a dynamic inventory extension of this problem and motivate the applicability of such models

joint inventory replenishment and pricing control for systems with uncertain yield and demand we study the joint inventory replenishment and pricing problem for production systems with random demand and yield more specifically we analyze the following single item periodic review model demands in consecutive periods are independent random variables and their distributions are price sensitive the production yield is uncertain so that the quantity received from a replenishment is a random variable whose distribution depends on the production quantity stockouts are fully backlogged our problem is to characterize the optimal dynamic policy that simultaneously determines the production quantity and the price for each period to maximize the total discounted profit we show that the optimal replenishment policy is of a threshold type i e it is optimal to produce if and only if the starting inventory in a period is below a threshold value and that both the optimal production quantity and the optimal price in each period are decreasing in the starting inventory we further study the operational e

a value of information approach to measuring risk in multi period economic activity abstract in this paper we discuss measures of risk for uncertain outcomes of economic activity which are based on the notion of the value of full information in stochastic programs information is measured in terms of algebras for multi period income streams information is represented by filtrations i e sequences of algebras the basic properties of our risk measures are multi period coherence diversification decreases risk compound concavity random alternatives increase risk and convex monotonicity insurance decreases risk

a single period stocking and pricing problem involving stochastic emergency supply abstract we develop a model for determining jointly optimal price and production policy of products with short life cycles subject to partially uncertain supply capacity within the price setting newsvendor framework we consider that demand in excess of the stocking quantity can be met by an emergency order due to the randomness of emergency supply capacity it may not always be possible to satisfy the demand completely assuming that all customers are charged the same price we explore the optimal sourcing and pricing decisions in the commonly used additive and multiplicative demand scenarios the first order conditions imply that the optimal price in the problem with random emergency supply is less than the optimal price associated with the deterministic demand problem when demand uncertainty is additive and it is greater than the optimal price associated with the deterministic demand problem when demand uncertainty is multiplicative we also find that the same type of comparative static applies in the multiplicative uncertainty case when there exists a dual source emergency system consisting of a perfectly reliable supplier and a second supplier with a stochastic capacity

uniqueness and indeterminacy on the dynamics of endogenous growth abstract in this paper we study the dynamics of endogenous growth both in the model of lucas and in a generalization that incorporates a labor leisure choice we characterize the regions of the parameter space that give rise to unique equilibria as well as the regions that yield a continuum of equilibria with positive growth rates we find that such multiple equilibria exist for empirically very plausible parameters in particular when the lucas model is modified to incorporate endogenous labor journal of economic literature numbers e00 e3 o40

unimodality of price setting newsvendor s objective function with multiplicative demand and its applications abstract we present a general solution framework for the price setting newsvendor problem with a multiplicative stochastic demand under mild assumptions such as increasing price elasticity on the mean demand function and increasing generalized failure rate on the distribution of the random factor we first prove that both the profit function with respect to price and its derived function with respect to order quantity are quasi concave three applications are then studied under our solution framework 1 we consider a wholesale price only contract by which a manufacturer sets a wholesale price and a newsvendor determines an order quantity and the retail price and show that the manufacturer s profit function is unimodal with respect to retailing price or stocking factor under certain conditions 2 we consider a newsvendor problem in which the demand depends on both the retail price and the level of sales effort and the cost exerting the sales effort is proportional to the order quantity we prove that there exists a unique pair of price and sales effort levels that maximize the total profit this result is established under a set of mild assumptions on the demand and cost functions 3 we identify a property in the single period profit function that satisfies condition 1 of huh and janakiraman 2008 which in turn guarantees the optimality of s s policy for an infinite stationary dynamic inventory price control system with lost sales and fixed order costs finally the unimodality of the newsvendor problem with a general stochastic and price sensitive demand is studied

stability global dynamics and markov equilibrium in models of endogenous economic growth abstract this paper studies the local and global dynamics of two sector models of endogenous growth with economy wide external effects and taxes on capital and labor the local analysis classifies the parameter space depending on the number of stationary solutions and local stability of equilibria the global analysis shows that if taxes are within certain bounds and the size of the external effects on the average level of human capital is smaller than the share of physical capital the equilibrium path is monotone and therefore a continuous markov equilibrium can be constructed

indeterminacy and sunspots with constant returns recently there has been a renewed interest in the possibility of indeterminacy and sunspots or alternatively put in the existence of a continuum of equilibria that arises in dynamic economies with some market imperfections much of the research in this area has been concerned with the empirical plausibility of indeterminacy in markets with external effects or with monopolistic competition and which exhibit some degree of increasing returns while the early results on indeterminacy relied on relatively large increasing returns and high markups more recently benhabib and farmer 1996a showed that indeterminacy can also occur in two sector models with small sector specific external effects and very mild increasing returns

optimal inventory decisions for a risk averse retailer when offering layaway abstract layaway allows economically disadvantaged budget constrained consumers to purchase expensive items through amortized payments and nominal program fees as opposed to using high interest financing options such as credit cards and payday loans we consider a risk averse retailer s ordering decisions when offering a layaway program we use the net loss and total loss functions found in the literature to determine a risk averse retailer s optimal order quantity under conditional value at risk cvar we next analyze the effects of the model parameters retailer s risk aversion the market default rate enrollment fee cancellation fee and so on on the optimal order quantity decisions we show that the optimal order quantity depends on different loss functions and different demand distribution functions further we show that as market default rate increases or the retailer becomes more risk averse then a rational retailer will not offer a layaway program

newsvendor solutions via conditional value at risk minimization abstract in this paper we consider the minimization of the conditional value at risk cvar a most preferable risk measure in financial risk management in the context of the well known single period newsvendor problem which is originally formulated as the maximization of the expected profit or the minimization of the expected cost we show that downside risk measures including the cvar are tractable in the problem due to their convexity and consequently under mild assumptions on the probability distribution of products demand we provide analytical solutions or linear programming lp formulation of the minimization of the cvar measures defined with two different loss functions numerical examples are also exhibited clarifying the difference among the models analyzed in this paper and demonstrating the efficiency of the lp solutions

optimal strategies for a three level contract farming supply chain with subsidy abstract we consider a three level contract farming supply chain with a risk averse farmer a risk neutral supplier and a risk neutral distributor in which the farmer faces a yield uncertainty and the government offers agricultural subsidy to the farmer the cvar criterion is used to describe the risk averse behavior of the farmer we derive the optimal strategies of the supply chain and perform some sensitivity analysis to investigate the effects of the government subsidy and other factors the results indicate that as the subsidy increases the farmer s total target production increases further analysis shows that the total production increase is mainly from the increased farm size and the farmer s endeavor actually decreases in addition the results indicate that the profits of the supplier and the distributor both increase with respect to the subsidy however the impact of the subsidy on the farmer s profit depends on the farmer s degree of risk averse in particular the impact of the subsidy to the farmer s profit tends to be positive for farmers with high degree of risk averse and the impact tends to be negative for those with low degree of risk averse the sensitivity analysis is also performed for the level of yield uncertainty in term of the standard deviation

coordination via cost and revenue sharing in manufacturer retailer channels abstract the problem of establishing efficiency in a manufacturer retailer channel channel coordination is extensively discussed in the industrial economics the marketing and the operations research literature however studies considering consumer demand to be simultaneously affected by price and non price variables are scarce one subset of models investigates efficient contracts with non linear tariffs but requires mechanisms which are rarely observed in managerial practice the other subset analyses channel efficiency effects of alternative royalty payments but omits to design an efficient contract we contribute to this literature by investigating a contract of royalty payments that is sufficient for channel coordination based on the analysis of the underlying vertical externalities we show that channel coordination requires cost and revenue sharing via a revenue sharing rate and marketing effort participation rates on both manufacturer and retailer level some surprising findings are highlighted there exists a continuum of efficient contracts efficiency requires a retailer s participation of at least 50 in the manufacturer s cost of marketing effort moreover the elimination of double marginalisation is not necessary for channel coordination manufacturer and retailer can choose an efficient contract via bargaining over the wholesale price the main challenge for managers will be to create acceptance of new types of royalty payments based on a trustful manufacturer retailer relationship we also discuss the cases of the apple iphone market launch and of innovative restaurant franchising to further illustrate and underline the relevance of our results

inventory cost rate functions with nonlinear shortage costs this article considers five cost rate models for inventory control each summarizing the expected holding and shortage costs per period as a function of the inventory position all models have linear holding costs and shortage cost coefficients of dimension unit period unit and period the latter two coeficients may be the shadow costs of a fill rate and a ready rate service constraint respectively one of the cost rate models is a new suggestion intended to facilitate modeling of periodic review inventory systems if and only if conditions on the demand process are presented for which the cost rate is quasi convex in the inventory position the typical sufficient condition requires that the cumulative demand distribution be logconcave a condition that is met by most demand distributions commonly used in the inventory literature the results simplify optimization and extend the known optimality of s s and nq r policies to cost structures common in applications and to the presence of typical service constraints as a prerequisite for the study a series of new monotonicity results are derived for compound renewal processes

the risk averse and prudent newsboy the effects of risk and risk aversion in the single period inventory newsboy problem are examined comparative static effects of changes in the various price and cost parameters are determined and related to the newsboy s risk aversion the addition of a random background wealth and of an increase in the riskiness of newspaper demand are also examined although many of the comparative effects generally are ambiguous some fairly simple restrictions on preferences and or risk increases are shown to lead to qualitatively deterministic results

the effect of risk aversion on distribution channel contracts implications for return policies the return policy is often used in retailing supply chains however it is controversial in judging their practical value in the literature various theoretical and modeling explanations of why the return policy is used in practice and is preferred by the retailer and manufacturer have been put forth the literature focusing on the channel agents risk attitudes to explain the adoption seems to have led to the conclusion that the two agents preferences for adopting the full return policy over the no return policy are always in conflict and thus the risk attitudes do not explain the adoption of return policy in practice in this paper we reinvestigate this issue we first identify two distinct phases of risk averseness high or low for each of the two agents we show distinct behaviors of how the wholesale price and order size are set in each phase then we show that the full return policy can be preferred over the no return policy by both the agents if both of them are high risk averse this implies that the agents risk attitudes can explain the adoption of return policy this is a new theoretical result which is contrary to the existing understanding in the literature our result highlights the importance and intricacy of channel policies especially when the risk attitudes of agents are considered

technical note a risk averse newsvendor model under the cvar criterion the classical risk neutral newsvendor problem is to decide the order quantity that maximizes the one period expected profit in this note we consider a risk averse newsvendor with stochastic price dependent demand we adopt conditional value at risk cvar a risk measure commonly used in finance as the decision criterion the aim of our study is to investigate the optimal pricing and ordering decisions in such a setting for both additive and multiplicative demand models we provide sufficient conditions for the uniqueness and existence of the optimal policy comparative statics show the monotonicity properties and other characteristics of the optimal pricing and ordering decisions we also compare our results with those of the newsvendor with a risk neutral attitude and a general utility function

a two sector model of endogenous growth with leisure in this paper we analyze a class of endogenous growth models with physical and human capital and with three altematives uses of time unqualified leisure work and education in contrast to some other related models we find that even in the absence of technological extemalities there could be multiple balanced paths we provide a characterization of the qualitative behavior of consumption leisure work and education over those balanced paths and study their transitional dynamics

fiscal policy and indeterminacy in models of endogenous growth this paper investigates the dynamic behavior of two sector models of endogenous growth with sector specific external effects and government expenditure financed by distortionary taxation when this type of external effect is combined with a sufficient degree of capital taxation in a lucas uzawa endogenous growth model continua of equilibria will emerge in the region of the balanced growth paths by contrast indeterminacy is not possible when either sector specific external effects or factor taxation are added to the model in isolation in the second part of the paper we demonstrate that if labor supply is endogenous indeterminacy can be consistent with much lower degrees of increasing returns to scale furthermore certain types of fiscal policy will be associated with multiple balanced growth paths and the existence of a poverty trap finally in the last part of the paper we demonstrate that if physical capital is employed in both sectors of the economy indeterminacy will emerge for varying combinations of factor taxation and external effects even when returns to scale are constant at the social level

mean variance analysis of supply chains under wholesale pricing and profit sharing schemes in this paper we explore the use of a wholesale pricing and profit sharing scheme wpps for coordinating supply chains under the mean variance mv decision framework we first analytically establish the necessary and sufficient conditions for coordinating the centralized supply chain by wpss we then show that there exists a unique equilibrium of the stackelberg game with wpps in the decentralized case after that we discuss the information asymmetric case in which the retailer can be benefited by pretending to be more risk averse finally we propose a new measure for the manufacturer to prevent this cheating from happening insights are generated

sustainable newsvendor models under trade credit abstract governments and industry are actively seeking means of reducing global warming the management of supply chains while taking into account the effects on the environment is an important issue therefore we present newsvendor models that take into account carbon emissions trade credit and product recycling in which the credit period affects the risk of default and the demand is uncertain in this paper the objective of these models is to determine the optimal ordering quantity credit period and recycle price in order to maximize total profits three carbon emission incentives are taken into account 1 carbon tax 2 direct cap 3 carbon cap and trade we also incorporate risk management methods to limit risk of default providing a solution for each type of carbon emission incentive numerical analysis is used to illustrate the implementation of solutions and the degree to which system parameters affect profits and decision making the results show that higher carbon taxes reduce recycle prices order quantities and total profits increasing the carbon cap leads to increases in recycle price order quantity and total profit a higher carbon price drives down the recycle price order quantity and total profits

an elasticity approach to the newsvendor with price sensitive demand we introduce a measure of elasticity of stochastic demand called the elasticity of the lost sales rate which offers a unifying perspective on the well known newsvendor with pricing problem this new concept provides a framework to characterize structural results for coordinated and uncoordinated pricing and inventory strategies concavity and submodularity of the profit function as well as sensitivity properties of the optimal inventory and price policies are characterized by monotonicity conditions or bounds on the elasticity of the lost sales rate these elasticity conditions are satisfied by most relevant demand models in the marketing and operations literature our results unify and complement previous work on price setting newsvendor models and provide a new tool for researchers modeling stochastic price sensitive demand in other contexts

coping with risk management and fill rate in the loss averse newsvendor model abstract in this paper we introduce the cvar conditional value at risk measure to hedge against the risks for the loss averse newsvendor we derive the optimal order quantities for the loss averse newsvendor to maximize the cvar objective of utility with and without the shortage cost respectively it is shown that when shortage cost is not considered an increase in the degree of loss aversion leads to a decrease in the fill rate therefore the newsvendor should strike a balance between the two conflicting targets in selecting the optimal order quantity when the shortage cost is taken into account and sufficiently large it is proved that an increase in the degree of loss aversion leads to an increase in the fill rate to manage both of the two targets the newsvendor should order more items in this case our sensitivity analysis further verifies that high risk implies high return and low risk comes with low return based on the analysis some management insights for the risk management of the loss averse newsvendor are presented

optimal decisions for the loss averse newsvendor problem under cvar abstract most of the existing literature about the newsvendor problem mainly focused on choosing an optimal order quantity to maximize the expected profit of a risk neutral newsvendor however some studies pointed out that in practice managers decisions as to order quantities always deviate from the profit maximization order quantity which is referred to as decision bias in the newsvendor problem then many studies introduced other preferences rather than risk neutrality of the newsvendor to explain such a decision bias this paper thus introduces loss aversion to the research of the newsvendor decision bias we propose a new definition to the loss averse newsvendor problem legacy loss which is defined either as the loss for excess order or the shortage penalty for lost sales when sales time is due the optimal decisions of a loss averse newsvendor are obtained through the following three ways i minimizing the expected legacy loss ii minimizing cvar of legacy loss by combining the cvar measure in risk management iii minimizing the combination of expected legacy loss and cvar of legacy loss and are compared with other existing results besides we present some properties of the optimal decisions as well as relations among them some numerical examples are given to illustrate the obtained results

a risk averse competitive newsvendor problem under the cvar criterion abstract we study a risk averse newsvendor problem with quantity competition and price competition under the conditional value at risk cvar criterion we characterize the optimal quantity and pricing decisions under both quantity and price competition for quantity competition we consider two demand splitting rules namely proportional demand allocation and demand reallocation although competition always leads to overstocking interestingly it does not necessarily lead to a profit loss in certain competitive environments such as demand reallocation by avoiding reducing overstocking that results from competition under the risk neutral criterion for price competition we consider both additive and multiplicative demand we find that the order quantity sale price and the expected profit decrease in the degree of risk aversion further both high price sensitivity and competition intensity force decision makers to lower their prices however high price sensitivity always reduces the order quantity while competition can have the opposite effect

divergence in economic performance transitional dynamics with multiple equilibria abstract special pairs of the utility functions and the production functions are used in this paper to uncover the transitional dynamics in a lucas model of growth the main findings are as follows a continuum of equilibria exists if the external effect of human capital in goods production is sufficiently large the process of lagging behind catching up with and overtaking that we often observe in the world economy can be explained finally some equilibrium paths are shown to have such complicated patterns that the dynamics conjectured by lucas are too simple to be correct journal of economic literature classification numbers o41 c61

a note on probability distributions with increasing generalized failure rates distributions with an increasing generalized failure rate igfr have useful applications in pricing and supply chain contracting problems we provide alternative characterizations of the igfr property that lead to simplify verifying whether the igfr condition holds we also relate the limit of the generalized failure rate and the moments of a distribution

a risk tolerance analysis for a joint price differentiation and inventory decisions problem with demand leakage effect abstract price differentiation is a commonly used practice in revenue management rm to improve a firm s profitability however most studies in the literature have considered a risk neutral firm to demonstrate the benefits of price differentiation the main contribution of this paper is in considering several important objectives while determining the optimal product prices and order production quantities for a risk adjusted firm with demand leakage effects in the presence of a price dependent stochastic demand the objectives considered include the maximization of a firm s expected profit and maximizing the probability of exceeding the risk adjusted expected revenue closed form expressions for optimal product prices and production quantities are derived for several of these objectives a numerical study is also presented to calibrate the impact of a firm s risk tolerance and other factors such as demand leakage market demand variability on the firm s profitability and its optimal decision

long run implications of investment specific technological change an attempt is made to disentangle its effects from the more traditional hicksneutral form of technological progress the balanced growth path for the model is characterized and calibrated to u s national income and product account nipa data the quantitative analysis suggests that investment specific technological change accounts for the major part of growth jel e13 030 041 047

newsvendor model with random supply and financial hedging utility based approach abstract this paper takes a utility based approach to the single period and single item newsvendor model unlike most models in the literature the newsvendor is not necessarily risk neutral and chooses the order quantity that maximizes the expected utility of the cash flow at the end of the period we suppose that there is uncertainty in demand as well as supply furthermore random demand and supply may be correlated with the financial markets the newsvendor exploits this correlation and manages his risks by investing in a portfolio of financial instruments the decision problem therefore includes not only the determination of the optimal ordering policy but also the selection of the optimal portfolio at the same time we first use a minimum variance approach to select the portfolio the analysis results in some interesting and explicit characterizations on the structure of the optimal policy we also present numerical examples to illustrate the effects of the parameters on the optimal order quantity and the importance of financial hedging on risk reduction

a risk averse newsvendor model under marketing dependency and price dependency abstract in this paper we analyze a single period inventory model where a risk averse newsvendor makes a joint decision on ordering pricing and marketing under the cvar risk measure criterion the newsvendor can exert marketing effort to enhance market demand we assume that the newsvendor s marketing effort affects the scale of the demand distribution and hence to model the marketing dependent demand as a multiplicative form we characterize sufficient conditions that guarantee existence and uniqueness of the optimal solutions under some mild assumptions on demand distribution expected demand function and marketing effort cost which are widely used in the related literature we show that the optimal order quantity increases in the newsvendor s marketing effort but the optimal price remains unchanged whether the demand is marketing dependent or not additionally we explore impact of exogenous parameters such as unit order cost salvage value and the newsvendor s risk aversion coefficient on the optimal decision variables and find that the optimal marketing effort always keeps the same changing direction with the optimal marketing independent order quantity as the exogenous parameters change this suggests that impact of the parameters on the optimal order quantity gets strengthened in the case of marketing dependent demand

analysis of a two sector model of endogenous growth with capital income taxation this paper addresses a two sector model of endogenous growth in which one sector produces final goods and the other produces new human capital both sectors employ human as well as physical capital under constant returns to scale technologies unlike existing studies of this type of model that have mostly concentrated on steady state analysis or on numerical simulations of calibrated models this paper presents an analytical argument concerning the dynamic behavior of the growth path and the effects of capital income taxation in and out of the steady growth equilibrium it is demonstrated that the dynamic behavior of the economy and some policy effects depend heavily upon the magnitude of factor intensity used in each production sector copyright 1996 by economics department of the university of pennsylvania and the osaka university institute of social and economic research association

research on rural to urban migration in ldcs the confusion frontier and why we should pause to rethink afresh abstract over 12 years of intensive research in the field of rural to urban migration have left the field beset with loss of direction and some serious doubts as to 1 whether research has really provided practitioners with more specific means of intervention 2 proper understanding of such intervention its justification and results 3 the areas in which the marginal benefit of extra research amounts to zero 4 those areas in which some consensus has emerged 5 which problem areas and specific issues merit intensive migration research in the coming years and 6 whether or not the academic profession has based its migration research effort in the past decade on an inappropriate set of presuppositions or even worse on invalid postulates a few examples of confusion and or fallacies that render this list more concrete are presented in this paper these are drawn from the areas of migration and fertility migration and education migration and the distribution of income by size migration and urban unemployment migration and the politics of economics migration and policy measures this paper then makes a plea for a major re evaluation which could and should provide a turning point in academic work and institutional thought the emphasis is on reformulation of the policy related presumptions on which research has been based for the past dozen years rather than trying to reach a better understanding of the decision making process generating rural to urban migration and its sectoral and overall social implications so as to devise more effective measures to contain reverse it the starting point should be an effort to effectively manipulate the phenomenon so as to turn it into a vehicle of national development and personal betterment