The difference between pure public goods and quasi-public goods;

From the point of view of consumption and use

Competitiveness refers to the characteristics that a product or service is consumed by one person, thus reducing the consumption of others. If someone has used a commodity (such as a train seat) and others can't use it at the same time, then the commodity is competitive in consumption.

From the perspective of cost, competitiveness means that letting more people consume will produce marginal costs, and a certain amount of things that one person has already consumed cannot be consumed by others at the same time. Generally speaking, if I want this thing, others can't want this thing.

Non-competitiveness, also known as "non-antagonism", "non-competition" or "non-reciprocity", means that the consumption of a product by some people will not affect the consumption of this product by others, and there is no conflict of interest among beneficiaries. In other words, under the condition that the quantity of a certain product is given, the marginal cost of increasing consumers is zero. In layman's terms, I can own this item and others can own this item on the premise that the quantity is determined.

From the point of view of interests

Exclusivity means that an article has characteristics that can prevent others from using it. After consumers purchase and obtain the right to consume goods, they can exclude other consumers from obtaining the benefits of the goods. Private products are exclusive in use, that is, my articles can only be disposed of by me and benefit from me.

Non-exclusive, that is, no one can exclude others from consuming the goods because of their own consumption. Generally speaking, what I use can be used by others, and I can benefit, and others can also benefit.

Secondly, through the understanding of the above concepts, we can clearly distinguish the competitiveness and exclusivity of private goods.

Pure public goods are completely non-competitive and non-exclusive goods. However, in real life, non-competitiveness and non-exclusivity do not necessarily exist at the same time. If only one kind of goods has one characteristic, it can be called quasi-public goods, that is, mixed goods.

Quasi-public products, also known as "mixed products", refer to limited non-competitive or limited non-exclusive public products, which are between pure public products and private products, such as education, government-built parks and crowded roads.

Compared with pure public goods, some of its properties have changed. The use and consumption of a quasi-public goods is limited in a certain area, and its benefit range is limited, such as local public goods (not necessarily exclusive); A kind of quasi-public goods is public or can be shared, and the use of one person cannot exclude the use of others. However, there may be competition in consumption for private interests. Due to the publicity, there may be problems of "crowding effect" and "overuse" in the use of commodities, such as groundwater basins and water resources, pastoral areas, forests and irrigation channels. Another kind of quasi-public goods is obviously exclusive and often needs to be paid for because of the existence of "crowded spots". This kind of quasi-public goods includes club goods, cable TV channels and highways.

Quasi-public goods are public goods with great externalities in consumption. It has two characteristics: ① competition in consumption, that is, one person's consumption of an item may reduce the consumption (quality and quantity) of others; ② Consumption is exclusive, that is, only those who pay by price can enjoy the item. There are a lot of quasi-public goods in reality, such as public facilities, public education and medical services in most cities.