Page 26 - CCFA Journal - Tenth Issue

数学建模 Math Modeling 加中金融

Inflation Index CPI

Inflation refers to the sustained increase in the general price level of goods and services in an economy over a period. It is usually
measured by the Consumer Price Index (CPI) or the Producer Price Index (PPI). When the general price level rises, each unit of
currency buys fewer goods and services; consequently, inflation reflects a reduction in the purchasing power of money – a loss of
real value in the medium of exchange and unit of account within an economy.

Source: Statistics Canada

Figure 1 CACPI

Consumer Price Index (CPI) is usually published by government agencies. For example, in Canada, CACPI is published by Statistics
Canada.

通膨指数（CPI）

通膨是指经济体中商品和服务的总体价格水平在一段时期内持续上升。通常用消费者物价指数（CPI）或生产者物价指数
（PPI）衡量。当总体价格水平上升时，每一单位货币可以购买的商品和服务会减少；因此，通膨反映了货币购买力的降
低，即经济中交换媒介和计价单位的实际价值的损失。

Year-on-Year CPI
Another form of CPI is quoted as Year-on-year Consumer Price Index (YoY CPI), a measure of inflation that compares the current
level of prices to the same period in the previous year. It is calculated by taking the current value of the CPI and subtracting the
value of the CPI from the same period in the previous year. The result is then divided by the value of the previous year's CPI and
multiplied by 100 to express it as a percentage change.
For example, if the current value of the CPI is 110 and the value of the CPI from the same period in the previous year is 100, the YoY
CPI would be (110 - 100) / 100 * 100 = 10%. This means that the overall prices of goods and services in the economy have increased
by 10% compared to the previous year.

YoY CPI is a commonly used measure of inflation because it provides a clear picture of the rate of price change over a specific time
period. It is also useful for comparing the rate of inflation across different countries or regions and for monitoring the evolution of
inflation over time.

同比 CPI

另一种 CPI 报价是以同比消费者物价指数（YoY CPI）形式，这是一种衡量通膨的指标，将当前的物价水平与上一年同一时
期的物价水平进行比较。它是通过计算当前的 CPI 值并减去上一年同一时期的 CPI 值来计算的。结果再除以上一年的 CPI
值并乘以 100，以百分比变化的形式表示。

例如，如果当前的 CPI 值为 110，上一年同一时期的 CPI 值为 100，则 YoY CPI 将为（110-100）/100 * 100 = 10％。这意味
着经济中商品和服务的总价格与上一年相比增加了 10％。

CCFA JOURNAL OF FINANCE March 2023
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