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Inflation is everywhere on newspaper, media, economic books, and reports. Even if you are economic and business enthusiastic, then better knowledge of inflation, its causes, and measurement tools can help bolster you. In this regards, this article is an attempt to answer the following questions:

• What is Inflation?
• Are there Benefits of Measuring Inflation?
• What are the Causes of Inflation?
• How to measure inflation?

inflation-measurements-problems

## What is Inflation?

Inflation is the rise of prices of all goods and services over time. In other way, it is a continues rise in general price level in economy. More precisely, inflation is a persistent and appreciable rise in general level of prices. Every price rise is not inflation, for it to be the inflation there must be a minimum rate at which price level must rise and minimum time period over which the price rise must continue.

When the prices of goods and services raise, it lowers the purchasing power of money and hurts the individuals and households. There is also a time when the prices of all goods and services continually decline, then this situation is deflation.

## What is Underlying Inflation?

Underlying inflation refers to the inflation that would have under normal economic conditions. It excludes the items having large price changes, or items highly volatile prices. The large swing in price may have come from supply disruption, infrequent changes in tax regulation, and other disturbances.

## Causes of Inflation

There are so many causes of inflation. Some classifies causes as internal vs external causes, while other demand-pull vs cost-push. In addition, there are plenty of theoretical explanations of causes of inflation. If you want to know more, please read this article 7 most important theories of inflation.

## Why to measure inflation?

The importance of measuring inflation includes –

• To measure the direct impact of price rise on life of citizens as the measure of cost of living.
• To formulate monetary policy that target price stability, whose measurement is provided by inflation.

## How is Inflation Measured?

There are 4 types of most significant measurements of inflation. They are:

• Consumer Price Index, CPI
• Producer’s Price Index, PPI
• Implicit GDP Deflator
• Personal Consumption Expenditure, PCE

## Consumer Price Index, CPI

It is the weighted average of change in prices of basket of goods and services a typical representative household consumes. The weight being given to typical items in the basket is based on how much households spend on these items. After that, We measure the inflation of items in relation to the previous period’s prices. The calculation of CPI takes place in some specific time intervals – yearly, quarterly, or monthly.

The actual measurement of CPI undergoes calculating inflation for each item in the basket, and then taking the weighted average of individual inflation of items in that basket. For the sake of mathematical exposition, let look at the following formula for measuring inflation for a single item:

$$\text{Inflation} = \frac{Price_{Period\ 2}\ – \ Price_{Period\ 1}}{Price_{Period\ 1}} * 100$$

After calculating the inflation for individual items, we take weighted average of all inflations to derive the CPI. Note that the other term for CIP is “headline index”.

### Problems of Consumer Price Index

Usages of consumer price index is so intensive that CPI virtually implies the inflation. Therefore, the problems of measuring CPI is nearly the problems of measuring inflation. Following are the problems of measuring CPI accurately and reliably:

#### Not a Indicator of Price Level:

CPI is a measure of price change in the economy but not the price level. This is so, because it only measures price change from the previous period. Suppose, for example, CPI of apple is 220 and CPI of banana is 150. Then CPI does not say that apple is more expensive than banana, it only tells that price of apple has increased more than banana. In fact, CPI measures the cost of purchasing ‘shopping basket’.

#### Cost of Living Standard:

CPI is not a measure of cost of living standard. Because, the cost of living measures the total spending required by household to maintain the given level of living standard or utility. But, CPI only measures the change in price, it cannot measure the household’s utility.

#### Substitution Bias:

Household’s spending pattern keeps on changing rapidly as there is change in the relative prices of goods. But, the CPI does not immediately update that spending patterns and creates the substitution bias.

#### Quality Bias:

Given that the quality of goods improves over time, the rise in price attributable to quality increase must be separated out from the any pure change in price. Not doing so will overestimate the CPI, thus introducing the quality bias.

#### Arrival of New Products:

New products that are available in the market are not immediately updated in the goods basket. The rise or fall in the prices of new products is not generally included for a few years.

#### Less Coverage:

CPI collects prices of items mostly from urban areas and it does not collect prices from rural or remote areas. Still, the CPI does not take into account the difference in spending patters between households. Some spends a lot more on one item than other, which introduces the bias in weight given to typical item in basket. This will lower the power of CPI to accurately measure the actual price change.

## Producer Price Index, PPI

It is a measure of average change in price received by the producers of goods and services. PPI is measured as the weighted average price of goods and services at the first commercial transaction by producer. In other terms, PPI measures the average movement of price change of goods and services as they leave producer. It excludes taxes, transports and trade margins that the purchaser would have to pay.

As oppose to CPI, which is a measurement of price movement from the perspective of purchaser, PPI is measurement of price movement from the perspective of seller. The purchasers’ and sellers’ price can differ because of the indirect taxes, subsidies, transports and trade margins.

The PPI indexes are published in various forms based on the classification of industry, product and end use. For this purpose, PPI calculation follows mainly three classification structures – Industry Classification, Commodity Classification (on the basis of similarity or material composition) and Commodity-based Final Demand-Intermediate Demand (FD-ID) System.

Generally the Bureau of Statistics of a country compiles PPI in an annual basis. The PPI is very important statistic for economic and business decision making, and monitoring inflation.

## Implicit GDP Deflator

Deflation of current GDP by some constant will produce the real GDP or constant price GDP. Therefore, the by-product of deflation process is the implicit GDP deflator. The implicit tag is, because the measurement of GDP deflator is not direct as the measurements of CPI and PPI. Instead, the calculation of GDP deflator follows the following formula.

$$\text{GDP Deflator} = \frac{Current\ GDP}{Real\ GDP} * 100$$

Unlike in CPI and PPI, GDP deflator is not based on fixed basket of goods and services, and is not necessary to assign weight to items. The assignment of weight to items is automatic in measurement of DGP deflator as the buyers vary their spending among different items.

DGP deflator measures more accurate pictures of the inflation in the economy than CPI. Thus implicit DGP deflator is important for economists, while CPI is important for consumers.

## Personal Consumption Expenditure, PCE

The alternative term for PCE is implicit price deflator. The reason for this alternative term is that, PCE is also the by-product of deflation process of current personal consumption expenditure. It is an index of price change of goods and services that are included in the personal expenditure component of Gross National Product, GNP. We get the PCE index dividing current personal consumption expenditure by real personal consumption expenditure.

It possesses the similar characteristics as the implicit GDP deflator. Moreover, there are considerations that PCE is more favorable tool of measuring inflation than CPI. Because it addresses some shortcomings of PCI like substitution bias.