英国兰卡斯特大学 (Lancaster University)：相对购买力平价PPP一系列商业评价

Relative PPP
相对购买力平价

• Relative PPP suggests that changes in the exchange rate should reflect changes in prices
相对购买力平价，汇率的变化应该反映价格变动
• The country with the higher inflation rate has a depreciating currency
该国的通胀率上升，货币贬值
  $/£S0 x [(1+if) / (1+i)] = $/£St
Where:
$/£S0 = $ per £ exchange rate at time 0
$/£St = Exchange rate at time t
i, if = expected inflation in UK, US
[(1+if) / (1+i)] >1 if US inflation > UK inflation – and this will mean US citizens need more $s to buy £1

Questions Relative PPP
相对购买力平价问题

For the following examples (1&2), what will the spot exchange rate be in one year according to relative PPP if:
对于下面的例子（1＆2），什么的即期汇率将在一年内根据相对购买力平价，如果：
• The spot exchange rate is $2 per £ today, expected inflation in the UK is 5% and in the USA is 3%?
即期汇率是2元每英镑今天，在英国的通胀预期是5％，而在美国为3％？
• The spot exchange rate is $2 per £ today, expected inflation in the UK is 4% and in the USA is 5%?
即期汇率是2元每英镑今天，在英国的通胀预期为4％，在美国是5％吗？
• Invert the formula for relative PPP so that it would be accurate for exchange rates quoted ‘in reverse’, i.e. number of £’s per $.
反转相对购买力平价的计算公式，所以，这将是准确的汇率报价'反向'，即英镑的每一美元。

Does PPP apply?
PPP是否适用？
http://ukthesis.org/gjswglzy

• There appears to be little evidence of PPP in the real world data, generally… why not?
有似乎是在现实世界中的数据，一般很少有证据的PPP......为什么不呢？
– PPP assumes that both countries record their prices with identical indexes – is this likely?
PPP假定，这两个国家具有相同的索引记录他们的价格 - 这是可能的吗？
• National variation in statistical practice
国家在统计实践中的变化
• National variation in the proportions of income people spend on certain goods – so weights vary
国家对某些商品消费收入人群的比例变化 - 这样的权重各不相同
– Non-traded goods:
非贸易品：
• Balassa (1964) and Samuelson (1964) both thought
巴拉萨（1964）和萨缪尔森（1964）都认为
– the proportion of non-traded goods in the index would cause differences – and the proportion of such goods could vary between countries.  Can you export a haircut? #p#分页标题#e#
非贸易商品在指数的比重会造成差异 - 此类商品的比例可能会有所不同的国家之间。你能出口理发？
– Transport costs varied due to ‘inherited’ characteristics such as location.
– 运输成本不同，由于'继承'的特征，如位置
• There could be significant differences due to these
由于这些有可能是显着的差异
• Similarly, IRP is often not quite followed by real exchange rates:
同样，IRP往往不太其次是实际汇率：
– Foreign or domestic capital movement is often restricted by governments, or is influenced by taxes on the exchange.
外国或国内的资本流动往往是由政府的限制，或受税收上的交流。
– Whilst this makes obvious impacts on capital mobility and therefore IRP, the RISK of such controls being imposed is an additional deterrent to capital mobility even where it does not currently exist
虽然这明显影响资本流动，因此IRP，被强加的风险控制资本流动是一个额外的威慑力，即使它目前不存在

Long-run conditions
长期运行条件

• Relative purchasing power parity holds better than PPP itself, and holds relatively well in the long run, although it is unlikely to precisely hold in any one period.
相对购买力平价成立优于PPP本身，从长远来看持有相对较好，虽然这是不可能精确地保持在任何一个时期。
• CIP does seem to almost hold, but interest rates are almost always slightly out:  many international firms are ready to move their borrowing in response to this (causing arbitrage effects) so that it does generally hold as an approximate condition
CIP似乎几乎持有，但利率几乎总是稍微：许多国际公司已准备好将他们的借贷反应（导致套利效果）的，所以，它并普遍认为作为一个近似条件

Answers Relative PPP
相对购买力平价答案

Remember:
  $/£S0 x [(1+if) / (1+i)] = $/£St
1. St = $2 x [ 1.03 / 1.05 ] = $1.96
2. St = $2 x [ 1.05 / 1.04 ] = $2.02
3. Invert the main part of the formula [(1+if) / (1+i)] so..
 £/$S0 x [(1+i) / (1+if)] = £/$St
(this is actually the form used in Eaker et al., as it is American)

Alternatives to forward exchange?
远期外汇的替代品？

• Loans can also be used to avoid the forward exchange problem.  E.g.  A company is owed $200,000 which will be repaid in 6 months.  The company can…
贷款也可以用来避免远期外汇问题。例如A公司欠下200,000美元，而且将在6个月内偿还。该公司可以...
– Find a forward exchange contract to fix a certain price on the movement of $200,000 into £s in 6 months; or#p#分页标题#e#
查找远期外汇合约Ş为英镑200,000元的运动解决一定的价格在6个月内;
– Borrow $(200,000-6 months interest charge) now and bring it home, leaving the $200,000 repayment to you, to repay the loan you have taken out in the US.  This would leave you with
借用$（200,000-6个月的利息费用），并把它带回家，留下20万美元偿还给你，你已经增加了在美国偿还贷款。这将使你
• $200,000.(1-(rUS/2)).S£/$.

Sources
来源

• Allen, L. (1997)  Capital Markets and Institutions:  a global view.  (London:  Wiley)
• Eaker, M.R., Fabozzi, F.J., & Grant, D. (1996)  International Corporate Finance.  (International Ed., London:  Dryden) Chapters 4-5