48624026-demand-forecasting

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Concepts of Forecasting:

The manager can conceptualize the future in definite terms. If he is concerned with future

event- its order, intensity and duration, he can predict the future. If he is concerned with the

course of future variables- like demand, price or profit, he can project the future. Thus

prediction and projection-both have reference to future; in fact, one supplements the other.Suppose, it is predicted that there will be inflation (event). To establish the nature of this

event, one needs to consider the projected course of general price index (variable). Exactly in

the same way, the predicted event of business recession has to be established with reference

to the projected course of variables like sales, inventory etc.

Thus, if a marketing manager fears demand recession, he must establish its basis in terms of

trends in sales data; he can estimate such trends through extrapolation of his available sales

data. This trend estimation is an exercise in forecasting.

Need for Demand Forecasting

Business managers, depending upon their functional area, need various forecasts. They need

to forecast demand, supply, price, profit, costs and returns from investments.

The question may arise: Why have we chosen demand forecasting as a model? What is the

use of demand forecasting?

The significance of demand or sales forecasting in the context of business policy decisions

can hardly be overemphasized. Sales constitute the primary source of revenue for the

corporate unit and reduction for sales gives rise to most of the costs incurred by the firm.

Demand forecasting is essential for a firm because it must plan its output to meet the

forecasted demand according to the quantities demanded and the time at which these are

demanded. The forecasting demand helps a firm to arrange for the supplies of the necessary

inputs without any wastage of materials and time and also helps a firm to diversify its output

to stabilize its income overtime.

The purpose of demand forecasting differs according to the type of forecasting.

(1) The purpose of the Short term forecasting:

It is difficult to define short run for a firm because its duration may differ according to thenature of the commodity. For a highly sophisticated automatic plant 3 months time may be

considered as short run, while for another plant duration may extend to 6 months or one year.

Time duration may be set for demand forecasting depending upon how frequent the

fluctuations in demand are, short- term forecasting can be undertaken by affirm for the

following purpose;

Appropriate scheduling of production to avoid problems of over production and

under- production.

Proper management of inventories

Evolving suitable price strategy to maintain consistent sales

Formulating a suitable sales strategy in accordance with the changing pattern of demand and extent of competition among the firms.



Forecasting financial requirements for the short period.

(2) The purpose of long- term forecasting:

The concept of demand forecasting is more relevant to the long-run that the short-run. It is

comparatively easy to forecast the immediate future than to forecast the distant future.Fluctuations of a larger magnitude may take place in the distant future. In fast developing

economy the duration may go up to 5 or 10 years, while in stagnant economy it may go up to

20 years. More over the time duration also depends upon the nature of the product for which

demand forecasting is to be made. The purposes are;

Planning for a new project, expansion and modernization of an existing unit,

diversification and technological up gradation.

Assessing long term financial needs. It takes time to raise financial resources.

Arranging suitable manpower. It can help a firm to arrange for specialized labour

force and personnel.

Evolving a suitable strategy for changing pattern of consumption.

Steps in Demand Forecasting

Demand or sales forecasting is a scientific exercise. It has to go through a number of steps. At

each step, you have to make critical considerations. Such considerations are categorically

listed below:

1) Nature of forecast: To begin with, you should be clear about the uses of forecast data-

how it is related to forward planning and corporate planning by the firm. Depending upon its

use, you have to choose the type of forecasts: short-run or long-run, active or passive,

conditional or non-conditional etc.

2) Nature of product: The next important consideration is the nature of product for which

you are attempting a demand forecast. You have to examine carefully whether the product is

consumer goods or producer goods, perishable or durable, final or intermediate demand, new

demand or replacement demand type etc. A couple of examples may illustrate the importance

of this factor. The demand for intermediate goods like basic chemicals is derived from the

final demand for finished goods like detergents. While forecasting the demand for basic

chemicals, it becomes essential to analyze the nature of demand for detergents. Promoting

sales through advertising or price competition is much less important in the case of

intermediate goods compared to final goods. The elasticity of demand for intermediate goodsdepends on their relative importance in the price of the final product.

Time factor is a crucial determinant in demand forecasting. Perishable commodities such as

fresh vegetables and fruits can be sold over a limited period of time. Here skilful demand

forecasting is needed to avoid waste. If there are storage facilities, then buyers can adjust

their demand according to availability, price and income. The time taken for such adjustment

varies from product to product. Goods of daily necessities that are bought more frequently

will lead to quicker adjustments. Whereas in case of expensive equipment which is worn out

and replaced after a long period of time, adaptation of demand will be spread over a longer

duration of time.



3) Determinants of demand: Once you have identified the nature of product for which you

are to build a forecast, your next task is to locate clearly the determinants of demand for the

product. Depending on the nature of product and nature of forecasts, different determinants

will assume different degree of importance in different demand functions.

In the preceding unit, you have been exposed to a number of price-income factors ordeterminants-own price, related price, own income-disposable and discretionary, related

income, advertisement, price expectation etc. In addition, it is important to consider socio-

psychological determinants, specially demographic, sociological and psychological factors

affecting demand. Without considering these factors, long-run demand forecasting is not

possible.

Such factors are particularly important for long-run active forecasts. The size of population,

the age-composition, the location of household unit, the sex-composition-all these exercise

influence on demand in. varying degrees. If more babies are born, more will be the demand

for toys; if more youngsters marry, more will be the demand for furniture; if more old people

survive, more will be the demand for sticks. In the same way buyers‟ ps ychology-his need,social status, ego, demonstration effect etc. – also effect demand. While forecasting you

cannot neglect these factors.

4) Analysis of factors &determinants: Identifying the determinants alone would not do,

their analysis is also important for demand forecasting. In an analysis of statistical demand

function, it is customary to classify the explanatory factors into (a) trend factors, which affect

demand over long-run, (b) cyclical factors whose effects on demand are periodic in nature,

(c) seasonal factors, which are a little more certain compared to cyclical factors, because

there is some regularly with regard to their occurrence, and (d) random factors which create

disturbance because they are erratic in nature; their operation and effects are not very orderly.

An analysis of factors is specially important depending upon whether it is the aggregate

demand in the economy or the industry‟s demand or the company‟s demand or the

consumers; demand which is being predicted. Also, for a long-run demand forecast, trend

factors are important; but for a short-run demand forecast, cyclical and seasonal factors are

important.

5) Choice of techniques: This is a very important step. You have to choose a particular

technique from among various techniques of demand forecasting. Subsequently, you will be

exposed to all such techniques, statistical or otherwise. You will find that different techniques

may be appropriate for forecasting demand for different products depending upon theirnature. In some cases, it may be possible to use more than one technique. However, the

choice of technique has to be logical and appropriate; for it is a very critical choice. Much of

the accuracy and relevance of the forecast data depends accuracy required, reference period

of the forecast, complexity of the relationship postulated in the demand function, available

time for forecasting exercise, size of cost budget for the forecast etc.

6) Testing accuracy: This is the final step in demand forecasting. There are various methods

for testing statistical accuracy in a given forecast. Some of them are simple and inexpensive,

others quite complex and difficult. This stating is needed to avoid/reduce the margin of error

and thereby improve its validity for practical decision-making purpose. Subsequently you

will be exposed briefly to some of these methods and their uses.



Techniques of Demand Forecasting

Broadly speaking, there are two approaches to demand forecasting- one is to obtain

information about the likely purchase behavior of the buyer through collecting expert‟s

opinion or by conducting interviews with consumers, the other is to use past experience as a

guide through a set of statistical techniques. Both these methods rely on varying degrees of judgment. The first method is usually found suitable for short-term forecasting, the latter for

long-term forecasting. There are specific techniques which fall under each of these broad

methods.

Simple Survey Method:

For forecasting the demand for existing product, such survey methods are often employed. In

this set of methods, we may undertake the following exercise.

1) Experts Opinion Poll: In this method, the experts on the particular product whose demand

is under study are requested to give their „opinion‟ or „feel‟ about the product . These experts,dealing in the same or similar product, are able to predict the likely sales of a given product

in future periods under different conditions based on their experience. If the number of such

experts is large and their experience-based reactions are different, then an average-simple or

weighted – is found to lead to unique forecasts. Sometimes this method is also called the

„hunch method‟ but it replaces analysis by opinions and it can thus turn out to be highly

subjective in nature.

2) Reasoned Opinion-Delphi Technique: This is a variant of the opinion poll method. Here

is an attempt to arrive at a consensus in an uncertain area by questioning a group of experts

repeatedly until the responses appear to converge along a single line. The participants are

supplied with responses to previous questions (including seasonings from others in the group

by a coordinator or a leader or operator of some sort). Such feedback may result in an expert

revising his earlier opinion. This may lead to a narrowing down of the divergent views (of the

experts) expressed earlier. The Delphi Techniques, followed by the Greeks earlier, thus

generates “reasoned opinion” in place of “unstructured opinion”; but this is still a poor proxy

for market behavior of economic variables.

3) Consumers Survey- Complete Enumeration Method: Under this, the forecaster

undertakes a complete survey of all consumers whose demand he intends to forecast, Once

this information is collected, the sales forecasts are obtained by simply adding the probable

demands of all consumers. The principle merit of this method is that the forecaster does notintroduce any bias or value judgment of his own. He simply records the data and aggregates.

But it is a very tedious and cumbersome process; it is not feasible where a large number of

consumers are involved. Moreover if the data are wrongly recorded, this method will be

totally useless.

4) Consumer Survey-Sample Survey Method: Under this method, the forecaster selects a

few consuming units out of the relevant population and then collects data on their probable

demands for the product during the forecast period. The total demand of sample units is

finally blown up to generate the total demand forecast. Compared to the former survey, this

method is less tedious and less costly, and subject to less data error; but the choice of sample

is very critical. If the sample is properly chosen, then it will yield dependable results;



otherwise there may be sampling error. The sampling error can decrease with every increase

in sample size

5) End-user Method of Consumers Survey: Under this method, the sales of a product are

projected through a survey of its end-users. A product is used for final consumption or as an

intermediate product in the production of other goods in the domestic market, or it may beexported as well as imported. The demands for final consumption and exports net of imports

are estimated through some other forecasting method, and its demand for intermediate use is

estimated through a survey of its user industries.

Complex Statistical Methods:

We shall now move from simple to complex set of methods of demand forecasting. Such

methods are taken usually from statistics. As such, you may be quite familiar with some the

statistical tools and techniques, as a part of quantitative methods for business decisions.

(1) Time series analysis or trend method: Under this method, the time series data on theunder forecast are used to fit a trend line or curve either graphically or through statistical

method of Least Squares. The trend line is worked out by fitting a trend equation to time

series data with the aid of an estimation method. The trend equation could take either a linear

or any kind of non-linear form. The trend method outlined above often yields a dependable

forecast. The advantage in this method is that it does not require the formal knowledge of

economic theory and the market, it only needs the time series data. The only limitation in this

method is that it assumes that the past is repeated in future. Also, it is an appropriate method

for long-run forecasts, but inappropriate for short-run forecasts. Sometimes the time series

analysis may not reveal a significant trend of any kind. In that case, the moving average

method or exponentially weighted moving average method is used to smoothen the series.

(2) Barometric Techniques or Lead-Lag indicators method: This consists in discovering a

set of series of some variables which exhibit a close association in their movement over a

period of time.

For example, it shows the movement of agricultural income (AY series) and the sale of

tractors (ST series). The movement of AY is similar to that of ST, but the movement in ST

takes place after a year‟s time lag compared to the movement in AY. Thus if one knows the

direction of the movement in agriculture income (AY), one can predict the direction of

movement of tractors‟ sale (ST) for the next year. Thus agricultural income (AY) may be

used as a barometer (a leading indicator) to help the short-term forecast for the sale of tractors.

Generally, this barometric method has been used in some of the developed countries for

predicting business cycles situation. For this purpose, some countries construct what are

known as „diffusion indices‟ by combining the movement of a number of leading series in the

economy so that turning points in business activity could be discovered well in advance.

Some of the limitations of this method may be noted however. The leading indicator method

does not tell you anything about the magnitude of the change that can be expected in the

lagging series, but only the direction of change. Also, the lead period itself may change

overtime. Through our estimation we may find out the best-fitted lag period on the past data,

but the same may not be true for the future. Finally, it may not be always possible to find out



the leading, lagging or coincident indicators of the variable for which a demand forecast is

being attempted.

3) Correlation and Regression: These involve the use of econometric methods to determine

the nature and degree of association between/among a set of variables. Econometrics, you

may recall, is the use of economic theory, statistical analysis and mathematical functions todetermine the relationship between a dependent variable (say, sales) and one or more

independent variables (like price, income, advertisement etc.). The relationship may be

expressed in the form of a demand function, as we have seen earlier. Such relationships,

based on past data can be used for forecasting. The analysis can be carried with varying

degrees of complexity. Here we shall not get into the methods of finding out „correlation

coefficient‟ or „regression equation‟; you must have covered those statistical techniques as a

part of quantitative methods. Similarly, we shall not go into the question of economic theory.

We shall concentrate simply on the use of these econometric techniques in forecasting.

We are on the realm of multiple regression and multiple correlation. The form of the equation

may be:

DX = a + b1 A + b2PX + b3Py

You know that the regression coefficients b1, b2, b3 and b4 are the components of relevant

elasticity of demand. For example, b1 is a component of price elasticity of demand. The

reflect the direction as well as proportion of change in demand for x as a result of a change in

any of its explanatory variables. For example, b2< 0 suggest that DX and PX are inversely

related; b4 > 0 suggest that x and y are substitutes; b3 > 0 suggest that x is a normal

commodity with commodity with positive income-effect.

Given the estimated value of and bi, you may forecast the expected sales (DX), if you know

the future values of explanatory variables like own price (PX), related price (Py), income (B)

and advertisement (A). Lastly, you may also recall that the statistics R2 (Co-efficient of

determination) gives the measure of goodness of fit. The closer it is to unity, the better is the

fit, and that way you get a more reliable forecast.

The principle advantage of this method is that it is prescriptive as well descriptive. That is,

besides generating demand forecast, it explains why the demand is what it is. In other words,

this technique has got both explanatory and predictive value. The regression method is

neither mechanistic like the trend method nor subjective like the opinion poll method. In this

method of forecasting, you may use not only time-series data but also cross section data. Theonly precaution you need to take is that data analysis should be based on the logic of

economic theory.

(4) Simultaneous Equations Method: Here is a very sophisticated method of forecasting. It

is also known as the „complete system approach‟ or „econometric model building‟. We do not

intend to get into the details of this method because it is a subject by itself. Moreover, this

method is normally used in macro-level forecasting for the economy as a whole; in this

course, our focus is limited to micro elements only. Of course, you, as corporate managers,

should know the basic elements in such an approach.

The method is indeed very complicated. However, in the days of computer, when packageprogrammes are available, this method can be used easily to derive meaningful forecasts. The



principle advantage in this method is that the forecaster needs to estimate the future values of

only the exogenous variables unlike the regression method where he has to predict the future

values of all, endogenous and exogenous variables affecting the variable under forecast. The

values of exogenous variables are easier to predict than those of the endogenous variables.

However, such econometric models have limitations, similar to that of regression method.

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48624026-demand-forecasting