Goods, Goods, Goods

某人問我：「又free goods，又public goods，其實Goods(商品)有幾多種嫁？Please。」

作為一個負責任ECON Blogger，我一定會招呼粉絲嘅提問。

DSE ECON課程提及Goods(商品)的確好多，但主要考核就有3大類別。

第一種：Economic Goods vs Free Goods

以稀少性為界限，可以將Goods分為Economics Goods同Free Goods。考評局Marking Scheme就曾經咁寫：

• A good is regarded as economics goods as more of it is preferred (to less of it).
• A good is regarded as free goods as only some of it is preferred (to none of it).

• Economic goods is defined when the quantity demanded is greater than the quantity supplied at zero price.
• Free goods is defined when the quantity demanded is smaller than the quantity supplied at zero price.

有時候我地仲可以話Economic Goods有Scarcity，Free Goods無。

當然仲有好多種論述，我好忙所以廢事寫咁多。另外，有讀過AL或者參考課外書，就會學到Bads(負值品)呢樣野，Bads are something that none of it is preferred. No one wants it.

第二種：Consumer Goods vs Producer Goods

以用途分類，Consumer Goods are goods which are for direct consumption/ satisfying wants. Producer Goods (又稱Capital Goods) are goods for further production.

Goods可以同時serve as Consumer Goods 同埋 Producer Goods。一個風筒可以當Consumer Goods自己吹頭，又可以喺salon當Producer Goods洗剪吹做生意。

第三種：Private Goods vs Public Goods

CE未見過，喺DSE隆重登場嘅分類方法。要參考大會指定答法，必然睇AL點寫。好多教科書都用rival in consumption同excludable嚟定義，但係始終你地得一次機會入大學，我就選擇答最保守嘅答案。

煙花是Public Good，因為可以同時Entertain好多人

參考下AL 2009年題目

AL 2009What is a public good? Give two real world examples of public goods that are produced privately, and explain why these private producers survive in the market. (8 marks)What is a public good?
Ø   A public good is a good subject to concurrent usages.
Ø   The consumption of a public good by one person will not diminish its availability to others.
Ø   It is the good when one individual uses, it will not impose any restriction on other individuals using the same good at the same time.
Ø   It is the good once it has been produced, the marginal cost of serving an extra user is zero.
Ø   The value of a public good to society is the combined value of all users who consume it; or the market demand curve for a public good is the vertical summation of individuals’ demand or MUV curves.
Why public goods successfully produced in the private market?Ø   It is because the transaction cost of excluding free-riders is not as high as economists traditionally thought of.

Give two real world examples of public goods that are produced privately.Ø   TV; radio
Ø   Music of Mozart/composers
Ø   Firework display of Disneyland (privately-produced)
Ø   Service of lighthouse (privately-produced)

Explain why these private producers survive in the market.Ø   TV; radio
n   Cable TV requires payment
n   Free TV like TVB and ATV offer commercial advertisement
Ø   Music
n   Music composed by musician is printed in CDs and sold to the public
n   Musicians who are alive can collect fee from copyright

世界上仲有好多有關Goods嘅分類，例如Merit Goods vs Demerit Goods, Exported Goods vs Imported Goods, Club Goods vs Common Resources. 有時間再寫下，希望幫到你 :)