số nhân trong chi tiêu công-1

Bài này đưa ra những vấn đề chung về số nhân chi tiêu công.

Số nhân là một trong những khái niệm cơ bản trong kinh tế vĩ mô. Tác động của nó có ảnh hưởng mạnh đến các chính sách vĩ mô đặc biệt là trong các kế hoạch phát triển của chính phủ dựa trên tăng trưởng kinh tế.

Số nhân chi tiêu công thể hiện tác động trong chi tiêu của chính phủ đối với tăng trưởng kinh tế mà trực tiếp là biến động GDP.

Có nhiều ảnh hưởng của chi tiêu chính phủ khi thực hiện một kế hoạch kích thích tổng cầu cả tích cực lẫn tiêu cực. Yếu tố tích cực thường có tác động trong ngắn hạn, ngay lập tức- thường được biểu hiện dưới hình thức tăng trưởng kinh tế, việc làm; và yếu tố tiêu cực thường đến trong dài hạn mà 2 ảnh hưởng tiêu cực nhất thường được nhắc đến là: lấn át đầu tư của khu vực tư và nợ công điều này có nguy cơ dẫn đến suy thoái kinh tế.

http://en.wikipedia.org/wiki/Fiscal_multiplier

In economics, the fiscal multiplier is the ratio of a change in national income to the change in government spending that causes it. More generally, the exogenous spending multiplier is the ratio of a change in national income to any autonomous change in spending (private investment spending, consumer spending, government spending, or spending by foreigners on the country's exports) that causes it. When this multiplier exceeds one, the enhanced effect on national income is called the multiplier effect. The mechanism that can give rise to a multiplier effect is that an initial incremental amount of spending can lead to increased consumption spending, increasing income further and hence further increasing consumption, etc., resulting in an overall increase in national income greater than the initial incremental amount of spending. In other words, an initial change in aggregate demand may cause a change in aggregate output (and hence the aggregate income that it generates) that is a multiple of the initial change.

The existence of a multiplier effect was initially proposed by Keynes student Richard Kahn in 1930 and published in 1931^[1]. Some other schools of economic thought reject or downplay the importance of multiplier effects, particularly in terms of the long run. The multiplier effect has been used as an argument for the efficacy of government spending or taxation relief to stimulateaggregate demand.

In certain cases multiplier values less than one have been empirically measured (an example is sports stadiums), suggesting that certain types of government spending crowd out private investment or consumer spending that would have otherwise taken place. This crowding out can occur because the initial increase in spending may cause an increase in interest rates or in theprice level.^[2] In 2009, because of the use of fiscal multipliers to project the benefits of the American Recovery and Reinvestment Act of 2009, The Economist magazine noted "economists are in fact deeply divided about how well, or indeed whether, such stimulus works"^[3] due to a lack of empirical data from non-military based stimulus. Immediately after the stimulus bill took effect, job loss slowed and private sector job growth resumed in 2010 and has continued through 2012^[4].

Applications

The multiplier effect is a tool used by governments to attempt to stimulate aggregate demand. This can be done in a period of recession or economic uncertainty. The money invested by a government creates more jobs, which in turn will mean more spending and so on.

The idea is that the net increase in disposable income by all parties throughout the economy will be greater than the original investment. When that is the case, the government can increase the gross domestic product by an amount that is greater than an increase in the amount it spends relative to the amount it collects in taxes.

The difference is the fiscal stimulus. The net fiscal stimulus may be increased by raising spending above the level of tax revenues, reducing taxes below the level of government spending, or any combination of the two that results in the government taxing less than it spends.

The resulting deficit spending must be financed from government reserves (if any) or net borrowing from private or foreign investors. If the money is borrowed, it must eventually be paid back with interest, such that the long term effect on the economy depends on the trade off between the immediate increase to the GDP and the long term cost of servicing the resulting government debt.

Because businesses hire based on profits earned and available work for new employees, and not money in pocket, the goal of best utilizing the multiplier effect is to seed the money as close to the consumer base as possible, where it can be spent on industries, who will then hire new employees, who will spend their paychecks on more industries, creating a cycle. The extent of the multiplier effect is dependent upon the marginal propensity to consume and marginal propensity to import. Also that the multiplier can work in reverse as well, so an initial fall in spending can trigger further falls in aggregate output.

The concept of the economic multiplier on a macroeconomic scale can be extended to any economic region. For example, building a new factory may lead to new employment for locals, which may have knock-on economic effects for the city or region.^[5]

Crowding out

It has been claimed that fiscal activity does not always lead to increased economic activity because deficit spending used to finance spending or tax cuts can crowd out financing for other economic activity. This phenomenon is argued to be less likely to occur in a recession, where savings rates are traditionally higher and capital is not being fully utilized in the private market.^[16]

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Marginal Propensity to Consume

As has been discussed, the Multiplier relies on the MPC (Marginal Propensity to Consume). The use of the term MPC here, is a reference to the MPC of a country (or similar economic unit) as a whole, and the theory and the mathematical formulae apply to this use of the term. However, individuals have an MPC, and furthermore MPC is not homogeneous across society. Even if it was, the nature of the consumption is not homogeneous. Some consumption may be seen as more benevolent (to the economy) than others. Therefore spending could be targeted where it would do most benefit, and thus generate the highest (closest to 1) MPC. This has traditionally been regarded as construction or other major projects (which also bring a direct benefit in the form of the finished product).

Clearly, some sectors of society are likely to have a much higher MPC than others. Someone with above average wealth or income or both may have a very low (short term, at least) MPC of nearly zero - saving most of any extra income. But a pensioner, for example, will have an MPC of 1 or even greater than 1. This is because a pensioner is quite likely to spend every penny of any extra income. Further, if the extra income is seen as regular extra income, and guaranteed into the future, the pensioner may actually spend MORE than the extra £1. This would occur where the extra income stream gives confidence that the individual does not need to put aside as much in the form of savings, or perhaps can even dip into existing savings.

More importantly, this consumption is much more likely to occur in local small business - local shops, pubs and other leisure activities for example. These types of businesses are themselves likely to have a high MPC, and again the nature of their consumption is likely to be in the same, or next tier of businesses, and also of a benevolent nature.

Other individuals with a high, and benevolent, MPC would include almost anyone on a low income - students, parents with young children, and the unemployed.

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Externalities

It has also been argued that over-reliance upon fiscal multipliers can lead to the neglect of externalities such as environmental degredation, unsustainable resource depletion or social consequences. Negative consequences of over-reliance upon fiscal multiplication values can either be envisaged in increased government spending on activities with high fiscal multiplication values which create negative externalities (pollution, climate change, resource depletion, etc.) or through decreased spending on activities which create low immediate fiscal multiplication values but create positive externalities (educational standards, social cohesion, public health, etc.)^[17].

Various types of fiscal multipliers

The following values are theoretical values based on simplified models, and the empirical values corresponding to the reality have been found to be lower (see below).

Note: In the following examples the multiplier is the right-hand-side equation without the first component.