Interpolation and Extrapolation Interpolation Interpolation consists in racing

Interpolation and Extrapolation

Interpolation: Interpolation consists in racing a valve which lies between 2 extreme points. The technique of estimating a past figure is termed as interpolation.

Assumption based on Interpolation:

• No sudden ups and downs: The first assumption of interpolation and extra polation is that within the given time period, no sudden ups and down or abrupt rise or fall we are to estimate the popullation for 1985 on the basis of 1951, 1961, 1971, 1981 and 1991 then we will have to assume that from 1951 to 1991 period no drastic changes have taken place.

• Regularily or uniformily of changes : The second assumption of interpolation and extrapolotion is that changes taking place in the given time period have regularily or uniformity rate of change is uniform during the given time period.

Difference between interpolation and extrapolation :

INTERPOLATION i) When some unknown Values at some place within the series is is estimated it is called interpolation. ii) Interpolation refers to the estimation of a figure at a value within the give data. iii) Interpolation provides missing link. iv) Interpolation is related with past. EXTRAPOLATION i) Whereas when some value outside the series is estimated it is called extrapolation. ii) It refers to the estimation of a figure or value outside the given limits of the data. iii) Extrapolation helps in precasting. iv) Extrapolation is related with periods chains about future.

Importance of Interpolation and Extrapolation:

i) Destruction of data –Sometime it happens that some data of the interveing period get destroyed due to flood. Fire, earthquake, etc. IN suck cases only by interpolation technique there data on account of being destroyed or lost can be estimated.

ii) To estimate the value for intermediate years : Figures related to some facts are collected at a fixed period or interval like population data in india are collected after every ten years. Estimation of population for some intermediate years can be made by interpolation technique only. iii) For future forecasting : By extrapolation method, future estimates can be made on the basis of available data. These estimates are very significant for industrialists, traders, goverment and economists. A successful plan can formulated on the basis of future estimaer and statistics only.

iv) For comparative study – When figures of 2 countries related to some particular problem are given for different years, then their comparison is not possible. By interpolation technique, a comparative study between 2 countries ca be made by obtaining the figures for the same period. v) Determination of median and mode : Interpolation method is used to find the values of median(M) , mode(Z) and quantities in a continuous series.

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