在A-level学习中经济学有些商场即price system是非常重要的一个章节，而要真实了解商场这一章的内容呢先要晓得的即是需要，Demand，那么影响需要改动的要素有哪些呢?咱们下面就来学习一下

　　1. Real income. If one's real income rose (real means 'allowing for inflation'), one should be able to afford more CDs.

　　2.The price of other goods. If the price of CD players rose then one would expect demand for CD players to fall, and so would the demand for CDs. These goods are complements. If the prices of rock concerts rose then one would expect the demand for these concerts to fall. Perhaps those who decided against the concert might buy a CD instead. These goods are substitutes.

　　3.Tastes and preferences. A slightly obscure but very important determinant. As you get older, you may lose interest in the repetitive music currently in the charts and try some original sounds from the 60s, 70s or 80s. Changing preferences will affect your demand for a product regardless of its price.

　　4. Expectations of future prices. If you think that the price for CDs is likely to fall in the near future, perhaps because of reduced production costs or competition from the US, you may delay some purchases which will reduce demand in the current time period. Alternatively, you may feel that CD prices are likely to rise in the near future, perhaps due to the lack of competition in the retail market, so you may increase your demand in the current time period.

　　5. Advertising. Although many of you probably doubt the effectiveness of some of the appalling adverts on the TV, one assumes that these companies would not spend fortunes on these adverts if they did not expect to see a significant rise in demand for the product in question (Virgin and Our Price are always trying to sell you CDs via the TV.)

　　影响产品商场需要量的要素：

　　1.报价 在其他条件不变的情况下，某一产品的报价越低，花费者对该产品的需要量越大;而产品的报价越高，花费者对该产品的需要量则越小。这即是经济学所说的需要法则。产品的报价是影响产品商场需要的最重要要素。

　　2.偏好 这儿所说的偏好，既与花费者的个人爱好和特性有关，也与全部社会习俗、传统习气、盛行时尚有关。一些时效性较强的产品(如盛行时装、音乐唱片)的需要对社会偏好非常灵敏，即使报价不变，由于社会时尚的改动，盛行时尚的变迁，需要量也会有急剧的改动。

　　3.收入 一般说来，收入与需要是正有关的，即别的条件不变的情况下，收入越高，对产品的需要越多，这是由于较高的收入代表了较高的采购才能和支付才能，而需要是受支付才能的束缚的。

　　4.有关产品报价 需要不只取决了产品本身的报价，也在相当程度上受其他产品报价的影响。在其他产品中，有两类两品的报价影响最大。一是代替品，即在花费中相当程度上可相互代替的产品，如猪肉与牛肉，可口可乐与百事可乐等，一般说来，某种产品的代替品报价越高，就显得这种产品相对廉价，因而对这种产品的需要会添加，反之则相反。例如，假如猪肉的报价上涨，牛肉的报价相对猪肉来说会显得较为廉价，大家就会用牛肉去代替猪肉，从而添加对牛肉的需要。二是互补品，即经常放在一起花费的产品，如钢笔与墨水，轿车与汽油等，明显，假如汽油报价暴升，使用轿车就会变得贵重，因而对轿车的需要会降低。因此，当某种产品的互补品价上涨时，这种产品的需要也会随之减少。

　　5.预期 这儿说的预期，不是指花费者的个人预期，而是指对产品需要产生影响的是社会的集体预期，无论这种预期准确与否。假如大家遍及预期某一产品将来报价会明显上涨，则会添加现时的花费，或多采购一些贮存起来。预期效应有时会带来报价越高，需要量越大的反常现象，这是由于大家遍及有“买涨不买跌”的心思。

　　以上内容即是A-level经济学商场有些，以及影响需要的要素，这一章的内容和咱们平时生活联络的较为严密对比好了解，并且对比重要，所以学习这一章的时分能够联络实际了解。