Governments intervene in markets to try and overcome market failure. The government may also seek to improve the distribution of resources (greater equality). The aims of government intervention in markets include 政府對市場進行干預，試圖克服市場失靈。政府也可能尋求改善資源的分配（更加平等）。政府干預市場的目的包括

• Stabilise prices 穩定價格
• Provide producers/farmers with a minimum income 為生產者/農民提供最低收入
• To avoid excessive prices for goods with important social welfare 避免具有重要社會福利的商品價格過高
• Discourage demerit goods/encourage merit good 抑制劣質商品/鼓勵優等商品

Forms of government intervention in markets 政府干預市場的形式

1. Minimum prices 最低價格
2. Maximum prices 最高價格
3. Minimum wages 最低工資
4. Nudges/Behavioural unit 誘導/行為單位

Minimum Prices 最低價格

This involves the government setting a lower limit for prices, e.g. the price of potatoes could not fall below 13p. 這涉及到政府為價格設定一個下限，例如，土豆的價格不能低于13便士。

The minimum price could be set for a few reasons 設定最低價格的原因有以下幾點:

• Increase farmers incomes 增加農民的收入
• Increase wages 增加工資
• Make demerit goods more expensive. For example, a minimum price for alcohol has been proposed. 使劣質商品更加昂貴。例如，有人提議為酒精設定最低價格。

Diagram Minimum Price 圖示 最低價格

A minimum price will lead to a surplus (Q3 – Q1). Therefore the government will need to buy the surplus and store it. Alternatively, it may impose quotas on farmers to decrease the quantity of the good put onto the market.

最低價格將導致盈余（Q3 - Q1）。因此，政府將需要購買過剩的產品并將其儲存起來。或者，政府可以對農民實行配額制，以減少投入市場的商品數量。

Problems of minimum prices 最低價格的問題

1. It could be costly for the government to buy the surplus 政府購買剩余產品的成本可能很高。
2. A minimum price guarantee acts as an incentive for farmers to try and increase supply. As an unintended consequence, the minimum price encourages more supply than expected and the cost for the government rises. This happened with the EEC Common Agricultural Policy. 最低價格保證是對農民嘗試增加供應的一種激勵。作為一個意外的結果，最低價格鼓勵了比預期更多的供應，政府的成本就會上升。這發生在歐共體的共同農業政策中。
3. To ensure minimum prices, the government may have to put tariffs on cheap imports – which damages the welfare of farmers in other countries. 為了確保最低價格，政府可能不得不對廉價進口產品征收關稅，這損害了其他國家農民的福利。

Maximum Price 最高價格

This involves putting a limit on any increase in price e.g. the price of housing rents cannot be higher than ￡300 per month. 這涉及到對任何價格增長的限制，例如，住房租金的價格不能高于每月300英鎊。

Maximum prices may be appropriate in markets where 最高價格可能適用于以下市場

• Suppliers have monopoly power and are able to generate substantial economic rent by charging high prices 供應商擁有壟斷權力，能夠通過收取高價產生大量經濟租金
• The good is socially important – e.g. good quality housing is important to labour productivity and a nations’ health. 商品具有社會重要性--例如，高質量的住房對勞動生產率和國家的健康非常重要。
• Demand is price inelastic because the good is necessary for maintaining minimum standards of living. 需求是無彈性的，因為該商品是維持最低生活標準所必需的。

Diagram Maximum Prices 圖示 最高價格

The Maximum price will be set below the equilibrium. This makes sure the price is less than the market clearing price. 最高價格將被設定在平衡價格之下。這確保了價格低于市場清算價格。

• However, the problem of a maximum price is that there will be a shortage. At Max Price, Demand is greater than supply. (Qe-Q1) This leads to queues and consumers unable to buy. 然而，最高價格的問題是，會出現短缺。在最高價格下，需求大于供給。(Qe-Q1)這導致了排隊，消費者無法購買。
• This will encourage the operation of black markets. 這將鼓勵黑市的運作。
• Therefore the government will have to ration the goods or increase supply 因此，政府將不得不對商品進行配給或增加供應。

evaluation 評價

If supply and demand are very inelastic, then a maximum price may have little adverse impact on creating shortages. For example, if supply housing for rent is very profitable, then a maximum price will not stop landlords putting the house on the market.

如果供應和需求非常缺乏彈性，那么最高價格可能對造成短缺沒有什么不利影響。例如，如果出租房屋的供應非常有利可圖，那么最高價格就不會阻止房東將房屋推向市場。

Buffer Stocks 緩沖庫存

Agriculture suffers from various problems. These include 農業受到各種問題的困擾。這些問題包括:

1. Fluctuating Prices 波動的價格
2. Uncertainty leads to lack of income 不確定性導致缺乏收入
3. Low-Income elasticity of demand 需求的低收入彈性
4. Positive Externalities of Farming 農業的正外部性

Therefore the government may feel there is a case to intervene and stabilise prices. A buffer stock involve a combination of minimum and maximum prices. The idea is to keep prices within a target price band. 因此，政府可能認為有必要進行干預并穩定價格。緩沖庫存涉及最低和最高價格的組合。其目的是將價格保持在一個目標價格范圍內。

Nudges 勸告

This is a different kind of government intervention. It is a government policy to influence demand indirectly. For example, putting cigarettes behind closed covers – makes it harder or less enticing for people to buy. 這是一種不同類型的政府干預。它是一種間接影響需求的政府政策。例如，把香煙放在封閉的蓋子后面--使人們更難或更不容易購買。

The government may also place flashing speed limit signs to give a smiley face to drivers under the speed limit, but an unhappy face to drivers exceeding the speed limit. 政府也可以放置閃爍的限速標志，給低于限速的司機一個笑臉，但給超過限速的司機一個不高興的表情。

Tax 稅收

Tax is a method to discourage consumption of certain goods. For example, taxes on demerit goods – goods with negative externalities. Taxes both discourage consumption and raise revenue for the government. 稅收是一種阻止某些商品消費的方法。例如，對劣質商品--具有負外部性的商品征稅。稅收既阻止了消費，又為政府增加了收入。

In the above example, the tax moves output to Q2 在上面的例子中，稅收將產出轉移到第二季度

Problems of tax 稅收的問題

• Demand may be inelastic 需求可能沒有彈性
• Hard for the government to know external cost and how much to tax 政府很難知道外部成本和征稅的數量
• May encourage tax evasion – e.g. rubbish tax can encourage fly-tipping 可能會鼓勵逃稅--例如，垃圾稅會鼓勵非法傾倒。

Subsidy 補貼

The government may subsidise goods with positive externalities (for example, public transport or education). 政府可以對具有正外部性的商品進行補貼（例如，公共交通或教育）。

In the above example, a subsidy shifts output to 120 (where SMB = SMC) so it is more socially efficient. 在上面的例子中，補貼將產出轉移到120（其中SMB=SMC），所以它的社會效率更高。

Problems of subsidies 補貼的問題

• Cost to government 政府的成本
• Subsidies may encourage firms to be inefficient because they can rely on government aid. 補貼可能會鼓勵企業效率低下，因為他們可以依賴政府的援助。