行为消费理论的拓展与应用研究

【作者】 那艺；

【导师】 贺京同；

【作者基本信息】 南开大学 ， 西方经济学， 2009， 博士

【副题名】以中国居民消费数据为例

【摘要】 本文的写作目的在于,通过对行为消费理论的既有研究实施拓展,构建一个能够描述个体长期偏好与短期偏好之冲突的跨期选择模型,从而对个体时间偏好率的形成机制进行解释,并用以分析改革开放以来我国居民消费行为的阶段性特征。本文的主要研究内容共为三部分。其一,本文对消费行为理论的缘起和发展做了简要回顾,并在此基础上指出,虽然生命周期假说与持久收入假说被作为新古典消费行为理论的两大基础,但实际上在这二者之间却存在着很大不同。其中,前者试图考察消费者怎样将其一生收入有效安排于每一期的使用,但后者却认为消费是由持久收入决定的,而持久收入的计算与消费者的时间偏好率有关,在连续时间状态下,时间偏好率的倒数可被近似地看作消费者计算持久收入的时长,根据经验测算,时间偏好率是一个很高的数值,意味着消费者用以计算持久收入的时间只有几年,亦即他的消费计划期限是几年而不是一生,这是一个更符合经验直觉的结论。然而,由于生命周期假说能更好地置于动态最优化的分析框架之中,而持久收入假说未能对时间偏好率的形成机制进行清晰的说明,因此经济学家逐渐遗弃了持久收入假说中富有启发意义的经验判断,而将其简单化地内嵌于生命周期假说之中,这种合二为一的方法就是新古典消费行为理论的基本研究范式,但毫无疑问的是,这种范式从其诞生之日起就必然在分析现实问题时面临很多困难。其二,在上述讨论的基础上,我们认为,通过对行为消费理论的既有研究实施合理拓展,可以对时间偏好率的形成机制进行一定说明,从而在消费行为理论中恢复持久收入假说被遗弃的观点。行为消费理论是指行为经济学在消费行为方面的既有研究成果,而行为经济学可被认为是新古典经济学对其固有研究框架进行质变突破的自我努力。在本文中,我们以行为消费理论中的双自我模型为基本分析框架,将个体视为由关心长期利益的计划者与关心眼前利益的行为者两种人格构成,并认为任何决策行为都是这两种人格力量的冲突产物。计划者要想尽量实现长期消费计划,就必须对每一期的行为者实施一定约束,方法是使用意志力或者是为行为者建立心理账户,这就是个体的自我控制行为。其中,建立心理账户是比使用意志力更为节省心理成本的方法,它具体是指,个体会将一生收入资源划分为当前可支配账户、当前资产账户与未来收入账户三部分,这些账户之间是不可完全替代的,并且每个账户的边际消费倾向是按顺序递减的,意味着个体可通过重新安排各账户内的资源来改变总体消费倾向。我们所要论证的是,当计划者通过建立心理账户来控制行为者的选择时,会导致最终的消费计划无法达到任何跨期一阶条件,其现实含义是,心理账户的约束可能会导致个体在仍具有扩大消费的意愿时却停止了进一步的消费,于是短期下的时间偏好率将维持在较高的水平上,这样就为持久收入假说的经验判断提供了一定的理论解释。其三,根据上述双自我模型的基本结论,本文对我国自改革开放以来的居民消费行为进行了研究。由于我国正处于经济体制转型时期,因此居民的消费行为也带有一定的阶段性特征。对此,我们将改革开放以来的时期划分为1978年至1990年的“不完全消费市场格局”与1991年至2007年的“建立完全消费市场”的两个阶段,并分别从短期消费波动对收入波动的敏感性以及长期消费增长与收入增长的关系两方面探讨了这种阶段性特征的存在性。在此基础上,本文对1978年以来我国居民的时间偏好率进行了测算,发现时间偏好率始终维持一个较高的水平,并且呈逐年递增的趋势,这意味着居民的消费计划期限正不断递减,根据双自我模型可以推知,这是由于居民消费的自我控制程度不断加深所致,亦即在其心理账户结构中,当前可支配账户的比例正逐渐降低,这是导致1990年以来我国居民消费需求持续低迷的重要原因。对此,我们考察了居民储蓄动机的跨阶段变化,发现谨慎动机、子女教育动机以及遗赠动机的提升是导致居民心理账户结构发生转变的原因,而这进一步与公共福利制度的变迁以及收入分配差距的扩大有关。据此,我们给出的政策建议是:一方面,政府应当对高收入者的当前资产账户与未来收入账户进行课税,如房产税与遗产税等,从而促使高收入者将部分财富从这些账户转移到诱惑力更强的当前可支配账户之中;另一方面,政府从高收入阶层所课征来的各种税收,不应全部以收入或转移支付的形式进行再分配,而应将其用于扩大社会保障与教育等公共福利方面的支出,这与简单的转移支付相比,能够更有效地“充实”较低收入者的当前资产账户与未来收入账户,从而使其无需将更多资源存储于这些诱惑力较低的账户之中。这样,各阶层居民的边际消费倾向都将得到提升,从而刺激现时消费水平的增长。更多还原

【Abstract】 The purpose of this paper is to develop a model of intertemporal choice on the basis of the behavioral consumption theory. The model incorporates the conflict of individual’s long-run preference and short-run preference and with which one can analysis the formation of time preference rate and stage characters of consumer behavior since Chinese Reform and Opening Up began. This paper is composed by three parts.First, we review the emergence and development of consumption theory. We will argue that, though the neoclassical consumption theory is rooted in the life-cycle hypothesis and the permanent income hypothesis, there are deep gaps between the two theories. The life-cycle hypothesis tries to reveal how consumer can arrange the uses of resources of the whole life effectively, while the permanent income hypothesis argues that consumption is determined by permanent income, which is related to the subjective rate of time preference. If the permanent income function is continuous, the inverse of time preference rate can be seen as the effective time span of calculating permanent income. The empirical evaluation shows that time preference rate is very high, which means that the effective time span of calculating permanent income is only several years. This follows the conclusion that the consumer planning horizon is rather shorter than the whole life time, which is more agreed with the empirical intuition. Unfortunately, the life-cycle hypothesis can be expressed as a dynamic maximization problem while the permanent income hypothesis cannot explain how the time preference rate is determined clearly. So economists abandon the empirical conclusion of permanent income hypothesis and integrate this hypothesis into the life-cycle hypothesis arbitrarily. This is the primary version of neoclassical consumption theory. Undoubtedly, this theory cannot explain and predict the real consumer behavior effectively.Second, we find that the determination of time preference rate can be described by the behavioral consumption theory with some modisfications, which can then make the abandoned viewpoint of the permanent hypothesis come back. The behavioral consumption theory is the research on consumer behavior based on the methodology of behavioral economics. Behavioral economics can be seen as the qualitative break of neoclassical economics. This paper is based on the dual-self model and assumes that any individual is composed of two personalities, one is planner who is concerned with the long-run preference and the other is doer who is concerned with the immediate preference. Thus, any decision can be seen as the conflict of the two personalities. The planner who wants to realize the long-run optimal consumption plan must impose some constraint on the does of each period. Willpower and mental account system is the two ways by which doers can be controlled. This is the self control problem of individual. Generally speaking, using mental account system is cheaper than willpower. There exist three main mental accounts which are current disposable account, current asset account, and future income account, respectively. These accounts are not fungible, and the marginal propensity to consume is assumed to be account specific, which means that individual can change the marginal propensity to consume by rearrange the structure of accounts. We will prove that when the planner controls the does by mental accounts, the final consumption plan cannot reach any first order condition. This means that the constraint by mental accounts may stop individual’s consumption even he has the willingness to consume. Thus time preference rate will be very high. This is a possible theoretical explanation to the empirical conclusion of the permanent hypothesis.Third, we investigate the consumer behavior since Chinese Reform and Opening Up began. Because of the reform, there exist obvious stage characters of consumer behavior. We divide the whole phase after 1978 into two stages, one is called "Imperfect Consumer Market" (1978-1990), the other is called "the Primal Progress of Consumer Market Reform" (1991-2007). We investigate the excess sensitiveness of short-term consumption fluctuation to income fluctuation and the relationship of long-term consumption growth with income growth. We find that the stage characters of consumer behavior cannot be negligent. Furthermore, we evaluate the consumer time preference rate since 1978. We find that the value of time preference rate is very high and increasing with years. This means that the consumer planning horizon is decreasing. With the implications of dual-self model, we can then predict that consumers impose more and more control on themselves and the proportion of current disposable account in mental account system is lower. This is why the consumer demand is insufficient since 1990. So we investigate the changes of saving motives of individuals and find that the precautionary motive, children-education motive and bequest motive are very intensive since 1990 which urge individuals to change their structure of mental account system. We will argue that the reform of public welfare system and the worsening of income distribution are two important reasons which can explain the changes of saving motives since 1990. This will be followed by some policy implications: On one hand, government should tax current asset account and future income account of the high-income population such as death tax and house tax, so that they may adjust their mental accounts structure and the proportion of current disposable account will be higher. On the other hand, government should raise the expenses on social security and public education rather than transfer payment. This will enlarge current asset account and future income account of the low-income population and they may store more spendable resources in current disposable account. Thus, the whole population will raise their propensities to consume and the consumption demand will increase.更多还原