假设一个经济体的名义利率为每年8％，但通货膨胀率为每年3％。这意味着，对于今天有人在银行里的每一美元，明年她将有1.08美元。然而，由于东西的价格增加了3％，她的1.08美元明年不会再购买8％的东西，明年它只能购买5％的东西。这就是实际利率为5％的原因。当名义利率与通货膨胀率相同时，这种关系尤其明显 – 如果银行账户中的钱每年赚取8％，但价格在一年中增加了8％，这笔钱就赚了一笔钱。归零。这两种情况都显示如下：费雪效应表明，为应对货币供应量的变化，通货膨胀率的变化如何影响名义利率。货币数量理论指出，从长远来看，货币供应量的变化会导致相应的通货膨胀量。此外，经济学家普遍认为，从长远来看，货币供应的变化对实际变量没有影响。因此，货币供应量的变化不应对实际利率产生影响。如果实际利率不受影响，那么通货膨胀的所有变化都必须反映在名义利率上，这正是费雪效应所声称的。
Suppose an economy has a nominal interest rate of 8% per year, but the inflation rate is 3% per year. This means that for every dollar that is in the bank today, she will have $1.08 next year. However, since the price of things has increased by 3%, her $1.08 will not buy 8% more next year, and next year it can only buy 5%. This is why the real interest rate is 5%. This relationship is especially pronounced when the nominal interest rate is the same as the inflation rate – if the money in the bank account earns 8% a year, but the price increases by 8% in a year, the money makes a fortune. Return to zero. Both of these conditions are shown below: The Fisher effect shows how changes in inflation affect nominal interest rates in response to changes in the money supply. The theory of quantity of money points out that in the long run, changes in the money supply will lead to corresponding inflation. In addition, economists generally believe that in the long run, changes in the money supply have no effect on actual variables. Therefore, changes in the money supply should not affect the real interest rate. If the real interest rate is not affected, then all changes in inflation must be reflected in the nominal interest rate, which is what the Fisher effect claims.