上一篇推送我们讲了a问最常见的题型（先说A再说B，evaluate到底是A还是B）对应的evaluation怎么写。
不过a问还有一些其他题型，需要ev的内容是不一样的。
今天我们来给大家过一下这些题型。
当然，ev的答案并不统一，所有的sample都仅供参考。
1. Evaluatethe framework
Mark scheme里关于evaluation有这样一个objectives:
- Recognise assumptions and limitations of economic information and models.
这里考察的是经济模型和实际情况的区别。
我们来看两个例子：
- Explain, with the help of examples, the significance of the size and sign of the coefficient of income elasticity of demand for the classification of a good and consider how confident you are of this classification.
AO2，我们会说旅游是luxury good，大米是necessity good，泡面是inferior good。
AO3，我们就需要讨论，这些商品的分类到底准不准确呢？
这里可以写的点有很多，最常见的例子就是对于不同收入的人来说，商品的分类是不同的。对有钱人来说，公共交通是inferior good; 对穷人来说，公共交通是necessity good. 因此，只依靠YED来区分商品并不合适的。
Sample: It's crucial to recognize that the classification of goods is not absolute but relative to the income of consumers: an inferior good for one person could be a necessity for someone else. For instance, public transportation is a necessary good for low-income earners because they use it for commuting. In contrast, high-income earners use private transportation for their commutes and only shift to public transportation when their income decreases. Therefore, while the income elasticity of demand provides a theoretical framework for classification, real-world application is more complex. Confidence in this classification increases when there's a clear understanding of the targeted consumers' income level.
-With the help of a formula, explain what is meant by the term price elasticity of demand for product and consider the extent to which it allows an entrepreneur to determine the effect of price changes on the total expenditure on their product.
AO2，我们会说如果价格上升/下降，不同的PED会对应不同的TR变化。
AO3，我们就需要讨论，实际情况是不是这样？
这里可以说的一个点就是市场是在随时发生变化的：如果有其他因素同时影响ped甚至demand，那公司的收入变化就可能不会按照PED所预计的那样。
Sample:The market is dynamic and subject to frequent changes. If consumers no longer favor the product, even though an entrepreneur raises prices for a price-inelastic product, the total expenditure will still fall due to a decrease in demand. Similarly, during economic downturns, consumers may become more sensitive to price changes, so that firms may not be able to rely on past data on PED to make decisions. Therefore, while the knowledge of PED provides a theoretical framework to determine how total expenditure changes with price, the actual impact in the real world is less certain. Other factors, such as changes in consumer tastes and income levels, also play a crucial role.
要答好这类题，大家需要在平时学习的时候就养成'one step further'的习惯：经济书上的理论有缺陷吗？在实际运用的过程中会遇到什么问题？
这也是这门课要考到93%+必须要掌握的。
2. Consider the extent
我们知道很多经济知识，比如price上升，consumer surplus下降。
但是consumer surplus下降了多少呢？由什么因素决定？
题目出现的extent这个词，就是你需要evaluate的内容。
我们看一个例子：
-With the help of a diagram(s), explain what is meant by equilibrium in a market, and consider the extent to which the equilibrium price and equilibrium quantity are likely to change for a product following an increase in the wages for labour across the whole economy.
AO2：工资上涨，normal goods的P和Q都上升，inferior goods的P和Q都下降。
但是，P和Q分别变化了多少呢？这就是我们需要在AO3里写的内容了。
这里可以写的点太多了，包括但不限于：
-工资到底涨了多少？
- YED大于1还是小于1？
-PES，PED
总之，虽然理论上我们知道normal goods和inferior goods对应的P和Q是怎么变化的，但是具体的变化幅度还需要很多额外的信息。
Sample:The extent of the change in quantity demanded will depend on the size of the actual wage change. If a consumer's wage increases significantly, they may completely stop purchasing certain inferior goods, such as instant noodles. This will lead to a more pronounced shift in the demand curve and a significant decrease in equilibrium quantity. However, if the wage change is marginal, the decrease in demand for inferior goods might be less noticeable. Therefore, without specific details about the goods and the scale of the wage changes, we could not draw a definitive conclusion about the direction and magnitude of changes in equilibrium price and quantity.
3. accurate argument
这也是CIE新考纲里出现的一类特色题目。
我们说evaluation通常都是主观的观点，有理有据即可，但CIE的有些a问对应的evaluation并不是这样，这些题目是有正确答案的。
我们来看两个例子：
- With the help of a diagram(s), explain what is meant by consumer surplus and producer surplus and consider whether a rise in the price of a product because of higher costs of production is likely to always reduce the consumer surplus.
今年夏季的考题，大家考完之后纷纷表示想不明白：S往左价格上升了，CS还能不下降的？为什么要讨论always？
那既然CS一定下降，你给出结论并说明原因就好啦。
Mark scheme:Following suitable analysis of PED, it can be concluded that the overall impactis that consumer surplus will always fall (1) with a conclusion that the extent ofthe fall is dependent on the value of the price elasticity of demand (1).
Sample:Consumer surplus is the difference between the price a consumer is willing to pay (WTP) for a product and its market price. A rise in the price of a product due to higher production costs will decrease the difference between a consumer's WTP and the market price. Therefore, consumer surplus will always fall. The extent of the fall depends on the value of the PED: inelastic demand will lead to a larger increase in market price and a greater decrease in consumer surplus.
- With the help of examples, explain the difference between free goods and public goods and consider the view that public goods can never be provided in a market economy. [8]
这是今年冬季的考题，虽然mark scheme还没有出来，但是我猜测market economy不能提供public good这个view依然是正确的，不需要进行正反面讨论。
当然，如果你学过课外知识，你可以说market economy会提供一些public goods，比如radio，然后通过广告来盈利。但是，根据CIE的考纲，market economy就是不提供public goods的。因此，直接给出原因+结论应该是可以的。
Sample:If a good is non-excludable and non-rivalrous, then an individual's cheapest option is to wait for someone else to pay for the good. The good’s non-excludability allows consumers to consume public goods for free, while its non-rivalrous nature means that an infinite number of people can free-ride in this manner. Since no single person would be willing to pay for the good themselves, no demand is registered in the market. Therefore, the view that public goods can never be provided in a market economy is correct, as there is no profit incentive for private enterprises to supply the good.
以上就是我们essay a问关于evaluation的全部内容，希望对大家的学习有所帮助。
【竞赛报名/项目咨询+微信：mollywei007】
