Investor's wiki

Base Period

Base Period

What is a Base Period?

A base period is a point in time for which data is accumulated and utilized as a benchmark against economic data from different periods to decipher them on a common basis. Base periods are in many cases utilized in finance and economics applications, for example, measuring inflation or different factors subject to change based on the progression of time.

Base period may likewise be alluded to as "reference period", "basis period", or "index period."

Figuring out Base Periods

The base period can be considered a common measuring stick for economic data. As opposed to expressing every data point in a series as a raw number, it can rather be stated as an extent or percentage of the data value in the base period. The value for the base period is generally set as the unit of measure, typically 1 or 100, and any remaining data points are restated as decimal, fractional, or percent values of the data value for that period.

Contrasting every data point with the base period can be a helpful method for taking care of data series that comprise of large or complex numbers. Every data point in the indexed series can then be effectively deciphered as the extent, percent change, or growth rate of the underlying data series over time, relative to the base period.


For instance, if a price index has a base year of 1990, and current prices are being compared to prices in that time span to develop a period series index, then the price level in any remaining years would be stated as a percentage of the 1990's price level. The price index for 1990 may be assigned a value of 100 and price levels for different years would have values relatively greater (or under) 100 with respect to the ratio of the genuine price levels of those years.

The calculation of the price level for 1995 may be calculated by taking the extent:
1990 price level100=1995 price levelx\frac{1990 \text}{100}=\frac{1995 \text}
furthermore, settling for x:
1990┬áprice┬álevel100├Ś1995┬áprice┬álevel=x\frac{1990\text}{100\times1995 \text}=
On the other hand, however less commonly, the base period might allude to contrasting every data point with a past data value utilizing a consistent interval of time instead of a steady base period. This technique doesn't make a predictable index comparison over time, however can assist with killing the effect of seasonal or short-term changes in data. Year-over-year, or month-over-month comparisons are instances of involving past data at a steady interval as a basis for comparison to current data.

The utilization of base periods to index data isn't obliged to financial applications. Numerous natural sciences likewise consistently utilize a base period as part of their logical processes. For example, to measure changes in global climate designs, base years must be laid out.

Base Period and the Base Effect

While building an index, the decision of a basis for comparison can influence how the data can be deciphered and ought to be selected carefully to enlighten the ideal objective that the data is being utilized for. Abnormal values or abnormal conditions in a base period can lead to comparisons that distort the trends in a data series. This distortion is once in a while called the base effect.

For instance, assume the City of New York foundations new building codes that become real on June first of a given year. In the period of May, builders scramble to start new building tasks to stay away from the expense of agreeing with the new codes. This could lead to a situation where the data for building begins show an abnormally high value for May and an abnormally low value for June, as builders climb their construction plans, which mirrors no underlying trend in the data, just the oddball regulatory change.

In this case, selecting the May or June data point as the base year in a comparison or to build a period series index would lead to ridiculously distorted brings about the subsequent transform data since each datum point in the index will contrast present data with an abnormally high (or low) value in the denominator. An analyst would be very much encouraged to pick a more ordinary value as the base period for the comparison of later data points.


  • Contrasting different data points with a steady base period allows analysts to spot changes and recognize long-term trends from short-term vacillations.
  • Base period alludes to the benchmark against which economic data from different periods is measured.
  • The decision a base period can influence a spectator's viewpoint on the data, which is known as the base effect.