口马歇尔一勒纳条件的建立在以上假设的基础上，马歇尔一勒纳条件认为，如果：(1b-1)Ex+Em>1(E表示对出口品需求的价格弹性Em表示对进口品需求的价格弹性。）那么货币贬值将改善国际收支中的贸易收支差额。p.23 para.3
6 马歇尔—勒纳条件的建立 在以上假设的基础上，马歇尔—勒纳条件认为，如果： Ex＋Em＞1 (1b-1) （Ex 表示对出口品需求的价格弹性 ；Em 表示对进口品需求的价 格弹性。） 那么货币贬值将改善国际收支中的贸易收支差额。 p. 23 para.3
口需求的价格弹性表示在一定时期内一种商品的需求量变动对于该商品的价格变动的反应程度。或者说，表示在一定时期内当一种商品的价格变化1%时所应引起的该商品需求量变化的百分比。通常用ed来代表需求价格弹性系数，英文为Priceelasticityofdemand(ED)。口需求的价格弹性系数=（需求量的变动率/价格的变动率）
7 需求的价格弹性表示在一定时期内一种商品的需求量变动对于该商品的价 格变动的反应程度。或者说，表示在一定时期内当一种商品的价格变化1%时 所应引起的该商品需求量变化的百分比。通常用ed来代表需求价格弹性系数， 英文为Price elasticity of demand (ED)。 需求的价格弹性系数 = - ( 需求量的变动率 ∕ 价格的变动率 )
There are three possible scenarios following adevaluation,and two effects in play onceacurrencyis devalued:1.Thepriceeffect-exports becomecheapermeasured in foreign currencyImportsbecomemoreexpensivemeasuredinthehome currency.2.Thevolume effect-thefactthat exportsbecomecheapershould encourageanincreased volumeofexports,andthefactthatimportsbecomemoreexpensiveshouldleadtoadecreasedvolumeofimports.The net effect depends uponwhethertheprice or volume effect dominates
There are three possible scenarios following a devaluation, and two effects in play once a currency is devalued: 1. The price effect – exports become cheaper measured in foreign currency. Imports become more expensive measured in the home currency. 2. The volume effect – the fact that exports become cheaper should encourage an increased volume of exports, and the fact that imports become more expensive should lead to a decreased volume of imports. The net effect depends upon whether the price or volume effect dominates
Figure2.1TheJ-curveeffectCurrentaccountSurplusTimeRDeficit
Figure 2.1 The J-curve effect
o Three of the most important are:-Atimelaginconsumerresponseo- Atimelaginproducerresponseo-Imperfectcompetition
Three of the most important are: - A time lag in consumer response - A time lag in producer response - Imperfect competition