# Fisher Effect 피셔효과(Fisher Effect)는 경제학에서 명목 금리, 실질 금리, 그리고 예상 인플레이션 간의 관계를 설명하는 이론입니다. 이 이론은 미국의 경제학자 어빙 피셔(Irving Fisher)에 의해 제안되었습니다. Equation 2 shows that in the long run, when all adjustments have occurred, an increase in inflation is fully reflected in nominal interest rates. Monetary policy becomes ineffective in changing the real interest rate. ## What is Fisher Effect 1. Liquidity Effect 2. ![[Fisher Effect.png]] Source: [Linkage between Interest Rates and Inflation](https://www.economicsdiscussion.net/inflation/linkage-between-interest-rates-and-inflation/3049) The **Fisher Effect** is an economic theory proposed by economist Irving Fisher that describes the relationship between ==nominal interest rates==, ==real interest rates==, and the ==expected inflation rate==. The Fisher Effect is central to understanding how inflation expectations influence interest rates in an economy. ### The Fisher Equation The core of the Fisher Effect is the **Fisher Equation**, which can be written as: $ \begin{align} (1 + i) = (1 + r) \times (1 + \pi_e) \end{align} $ Where: - $i$ is the nominal interest rate. - $r$ is the real interest rate. - $\pi_e$ is the expected inflation rate. ### Simplified Fisher Equation For most practical purposes, especially when the rates are low, the Fisher Equation can be approximated by subtracting 1 from both sides: $ \begin{align} i \approx r + \pi_e \end{align} $ This approximation works because the product of $r$ and $\pi_e$ (which is typically small) can be neglected. ### Derivation The Fisher Effect can be derived by considering the relationship between real returns, nominal returns, and inflation. The nominal interest rate is the rate of interest you earn without adjusting for inflation, while the real interest rate is adjusted for the effects of inflation. Starting from the real return on an investment: $ \begin{align} 1 + r = \frac{1 + i}{1 + \pi_e} \end{align} $ Multiplying both sides by $1 + \pi_e$ to isolate $1 + i$: $ \begin{align} (1 + r) \times (1 + \pi_e) = 1 + i \end{align} $ Expanding the right side: $ \begin{align} 1 + r + \pi_e + r\pi_e = 1 + i \end{align} $ Thus, the Fisher Equation is: $ \begin{align} 1 + i = (1 + r)(1 + \pi_e) \end{align} $ As mentioned earlier, for small values of $r$ and $\pi_e$, the equation simplifies to: $ \begin{align} i \approx r + \pi_e \end{align} $ This shows that the nominal interest rate is approximately equal to the real interest rate plus the expected inflation rate. ### Implications The Fisher Effect has several key implications: 1. **Inflation Expectations**: If people expect higher inflation in the future, nominal interest rates tend to rise. This is because lenders will demand higher nominal rates to compensate for the decrease in purchasing power due to inflation. (ALLEE: This is the KEY assumption) 2. **Monetary Policy**: Central banks monitor inflation expectations closely. If inflation expectations rise, central banks may increase nominal interest rates to prevent real interest rates from falling too low, which could overstimulate the economy and further fuel inflation. 3. **International Finance**: The Fisher Effect is also relevant in international finance. Differences in nominal interest rates between two countries often reflect differences in expected inflation rates. This relationship is a key factor in determining exchange rates. 4. **Investment Decisions**: For investors, understanding the Fisher Effect is crucial. If an investor expects high inflation, they may seek investments that offer higher nominal returns to maintain their real purchasing power. ### Example Suppose the real interest rate $r$ is 2%, and the expected inflation rate $\pi_e$ is 3%. According to the Fisher Effect: $ \begin{align} i \approx 2\% + 3\% = 5\% \end{align} $ This means that in an environment with a 3% expected inflation rate, the nominal interest rate would be approximately 5%. ### Conclusion The Fisher Effect is a fundamental concept in economics that explains how inflation expectations are embedded in nominal interest rates. Understanding this relationship is vital for monetary policy, investment decisions, and the broader understanding of macroeconomic dynamics. ## 피셔효과의 핵심 개념: 1. **명목 금리 (Nominal Interest Rate):** - 금융기관이 대출할 때 적용하는 표면적인 금리로, 인플레이션을 반영하지 않은 금리입니다. 2. **실질 금리 (Real Interest Rate):** - 명목 금리에서 인플레이션율을 뺀 값으로, 실제로 자금의 구매력이 얼마나 증가했는지를 나타내는 금리입니다. 3. **예상 인플레이션 (Expected Inflation):** - 미래에 예상되는 인플레이션율로, 사람들이 물가가 어떻게 변할지에 대한 기대를 나타냅니다. ## 피셔 방정식: 피셔효과는 다음과 같은 방정식으로 표현됩니다: $ \begin{align} \text{명목 금리} = \text{실질 금리} + \text{예상 인플레이션} \end{align} $ 이 방정식은 다음과 같은 의미를 가집니다: - **명목 금리:** 금융시장에서 일반적으로 공시되는 이자율. - **실질 금리:** 물가 상승률을 고려한 후 남는 이자율. - **예상 인플레이션:** 미래에 예상되는 물가 상승률. ## 예시: 만약 은행의 명목 금리가 5%이고, 예상 인플레이션율이 2%라면, $ \begin{align} \text{실질 금리} = 5\% - 2\% = 3\% \end{align} $ 즉, 실질적으로 구매력 측면에서 3%의 수익을 얻고 있다고 볼 수 있습니다. ## 피셔효과의 의미: 1. **인플레이션 반영:** - 투자자들은 미래의 구매력을 유지하기 위해 최소한 예상 인플레이션 만큼의 추가 수익을 요구하게 됩니다. 2. **금융 정책:** - 중앙은행이나 금융 당국이 통화 공급을 늘려 단기적으로 명목 금리를 낮추더라도, 장기적으로는 예상 인플레이션이 올라감에 따라 명목 금리가 다시 상승할 가능성이 높습니다. 따라서 피셔효과는 명목 금리가 실질적 구매력 변화와 기대되는 인플레이션을 모두 반영하고 있다는 점에서 중요합니다.