FORCASTING
INTRODUCTION
THE
GROWING COMPETITION, FREQUENT CHANGES IN CUSTOMER'S DEMAND AND THE TREND
TOWARDS AUTOMATION DEMAND THAT DECISIONS IN BUSINESS SHOULD NOT BE BASED PURELY
ON GUESSES RATHER ON A CAREFUL ANALYSIS OF DATA CONCERNING THE FUTURE COURSE OF
EVENTS. MORE TIME AND ATTENTION SHOULD BE GIVEN TO THE FUTURE THAN TO THE PAST,
AND THE QUESTION 'WHAT IS LIKELY TO HAPPEN?' SHOULD TAKE PRECEDENCE OVER 'WHAT
HAS HAPPENED?' THOUGH NO ATTEMPT TO ANSWER THE FIRST CAN BE MADE WITHOUT THE
FACTS AND FIGURES BEING AVAILABLE TO ANSWER THE SECOND. WHEN ESTIMATES OF
FUTURE CONDITIONS ARE MADE ON A SYSTEMATIC BASIS, THE PROCESS IS CALLED
FORECASTING AND THE FIGURE OR STATEMENT THUS OBTAINED IS DEFINED AS FORECAST.
IN A
WORLD WHERE FUTURE IS NOT KNOWN WITH CERTAINTY, VIRTUALLY EVERY BUSINESS AND
ECONOMIC DECISION RESTS UPON A FORECAST OF FUTURE CONDITIONS. FORECASTING AIMS
AT REDUCING THE AREA OF UNCERTAINTY THAT SURROUNDS MANAGEMENT DECISION-MAKING
WITH RESPECT TO COSTS, PROFIT, SALES, PRODUCTION, PRICING, CAPITAL INVESTMENT,
AND SO FORTH. IF THE FUTURE WERE KNOWN WITH CERTAINTY, FORECASTING WOULD BE
UNNECESSARY. BUT UNCERTAINTY DOES EXIST, FUTURE OUTCOMES ARE RARELY ASSURED
AND, THEREFORE, ORGANIZED SYSTEM OF FORECASTING IS NECESSARY. THE FOLLOWING ARE
THE MAIN FUNCTIONS OF FORECASTING:
- THE CREATION OF
PLANS OF ACTION.
- THE GENERAL USE
OF FORECASTING IS TO BE FOUND IN MONITORING THE CONTINUING PROGRESS OF
PLANS BASED ON FORECASTS.
- THE FORECAST
PROVIDES A WARNING SYSTEM OF THE CRITICAL FACTORS TO BE MONITORED
REGULARLY BECAUSE THEY MIGHT DRASTICALLY AFFECT THE PERFORMANCE OF THE
PLAN.
IT IS
IMPORTANT TO NOTE THAT THE OBJECTIVE OF BUSINESS FORECASTING IS NOT TO
DETERMINE A CURVE OR SERIES OF FIGURES THAT WILL TELL EXACTLY WHAT WILL HAPPEN,
SAY, A YEAR IN ADVANCE, BUT IT IS TO MAKE ANALYSIS BASED ON DEFINITE
STATISTICAL DATA, WHICH WILL ENABLE AN EXECUTIVE TO TAKE ADVANTAGE OF FUTURE
CONDITIONS TO A GREATER EXTENT THAN HE COULD DO WITHOUT THEM. IN FORECASTING
ONE SHOULD NOTE THAT IT IS IMPOSSIBLE TO FORECAST THE FUTURE PRECISELY AND THERE
ALWAYS MUST BE SOME RANGE OF ERROR ALLOWED FOR IN THE FORECAST.
DEPENDENT VERSUS INDEPENDENT DEMAND
DEMAND OF
AN ITEM IS TERMED AS INDEPENDENT WHEN IT REMAINS UNAFFECTED BY THE DEMAND FOR
ANY OTHER ITEM. ON THE OTHER HAND, WHEN THE DEMAND OF ONE ITEM IS LINKED TO THE
DEMAND FOR ANOTHER ITEM, DEMAND IS TERMED AS DEPENDENT. IT IS IMPORTANT TO
MENTION THAT ONLY INDEPENDENT DEMAND NEEDS FORECASTING. DEPENDENT DEMAND CAN BE
DERIVED FROM THE DEMAND OF INDEPENDENT ITEM TO WHICH IT IS LINKED.
BUSINESS TIME SERIES
THE FIRST
STEP IN MAKING A FORECAST CONSISTS OF GATHERING INFORMATION FROM THE PAST. ONE
SHOULD COLLECT STATISTICAL DATA RECORDED AT SUCCESSIVE INTERVALS OF TIME. SUCH
A DATA IS USUALLY REFERRED TO AS TIME SERIES. ANALYSTS PLOT DEMAND DATA ON A
TIME SCALE, STUDY THE PLOT AND LOOK FOR CONSISTENT SHAPES AND PATTERNS. A TIME
SERIES OF DEMAND MAY HAVE CONSTANT, TREND, OR SEASONAL PATTERN.
OR SOME
COMBINATION OF THESE PATTERNS. THE FORECASTER TRIES TO UNDERSTAND THE REASONS
FOR SUCH CHANGES, SUCH AS,
- CHANGES THAT
HAVE OCCURRED AS A RESULT OF GENERAL TENDENCY OF THE DATA TO INCREASE OR
DECREASE, KNOWN AS SECULAR MOVEMENTS.
- CHANGES THAT
HAVE TAKEN PLACE DURING A PERIOD OF 12 MONTHS AS A RESULT IN CHANGES IN
CLIMATE, WEATHER CONDITIONS, FESTIVALS ETC. ARE CALLED AS SEASONAL
CHANGES.
- CHANGES THAT
HAVE TAKEN PLACE AS A RESULT OF BOOMS AND DEPRESSIONS ARE CALLED AS
CYCLICAL VARIATIONS.
- CHANGES THAT
HAVE TAKEN PLACE AS A RESULT OF SUCH FORCES THAT COULD NOT BE PREDICTED
(LIKE FLOOD, EARTHQUAKE ETC.) ARE CALLED AS IRREGULAR OR ERRATIC
VARIATIONS.
QUANTITATIVE APPROACHES OF FORECASTING
MOST OF
THE QUANTITATIVE TECHNIQUES CALCULATE DEMAND FORECAST AS AN AVERAGE FROM THE
PAST DEMAND. THE FOLLOWING ARE THE IMPORTANT DEMAND FORECASTING TECHNIQUES.
SIMPLE
AVERAGE METHOD: A SIMPLE AVERAGE OF DEMANDS OCCURRING IN ALL PREVIOUS TIME
PERIODS IS TAKEN AS THE DEMAND FORECAST FOR THE NEXT TIME PERIOD IN THIS
METHOD.
EXAMPLE 1
SIMPLE AVERAGE
A XYZ TELEVISION SUPPLIER FOUND A DEMAND OF 200 SETS IN JULY, 225
SETS IN AUGUST & 245 SETS IN SEPTEMBER. FIND THE DEMAND FORECAST FOR THE
MONTH OF OCTOBER USING SIMPLE AVERAGE METHOD.
THE AVERAGE DEMAND FOR THE MONTH OF OCTOBER IS
SIMPLE
MOVING AVERAGE METHOD: IN THIS METHOD, THE AVERAGE OF THE DEMANDS FROM SEVERAL
OF THE MOST RECENT PERIODS IS TAKEN AS THE DEMAND FORECAST FOR THE NEXT TIME
PERIOD. THE NUMBER OF PAST PERIODS TO BE USED IN CALCULATIONS IS SELECTED IN
THE BEGINNING AND IS KEPT CONSTANT (SUCH AS 3-PERIOD MOVING AVERAGE).
EXAMPLE 2
SIMPLE MOVING AVERAGE:
A XYZ
REFRIGERATOR SUPPLIER HAS EXPERIENCED THE FOLLOWING DEMAND FOR REFRIGERATOR
DURING PAST FIVE MONTHS.
MONTH
|
DEMAND
|
FEBRUARY
|
20
|
MARCH
|
30
|
APRIL
|
40
|
MAY
|
60
|
JUNE
|
45
|
FIND OUT
THE DEMAND FORECAST FOR THE MONTH OF JULY USING FIVE-PERIOD MOVING AVERAGE
& THREE-PERIOD MOVING AVERAGE USING SIMPLE MOVING AVERAGE METHOD.
- WEIGHTED MOVING
AVERAGE METHOD: IN THIS METHOD, UNEQUAL WEIGHTS ARE ASSIGNED TO THE PAST
DEMAND DATA WHILE CALCULATING SIMPLE MOVING AVERAGE AS THE DEMAND FORECAST
FOR NEXT TIME PERIOD. USUALLY MOST RECENT DATA IS ASSIGNED THE HIGHEST
WEIGHT FACTOR.
EXAMPLE 3
WEIGHTED MOVING AVERAGE METHOD:
THE
MANAGER OF A RESTAURANT WANTS TO MAKE DECISION ON INVENTORY AND OVERALL COST.
HE WANTS TO FORECAST DEMAND FOR SOME OF THE ITEMS BASED ON WEIGHTED MOVING
AVERAGE METHOD. FOR THE PAST THREE MONTHS HE EXPRIENCED A DEMAND FOR PIZZAS AS
FOLLOWS:
MONTH
|
DEMAND
|
OCTOBER
|
400
|
NOVEMBER
|
480
|
DECEMBER
|
550
|
FIND THE
DEMAND FOR THE MONTH OF JANUARY BY ASSUMING SUITABLE WEIGHTS TO DEMAND DATA.
- EXPONENTIAL
SMOOTHING METHOD: IN THIS METHOD, WEIGHTS ARE ASSIGNED IN EXPONENTIAL
ORDER. THE WEIGHTS DECREASE EXPONENTIALLY FROM MOST RECENT DEMAND DATA TO
OLDER DEMAND DATA.
EXAMPLE 4
EXPONENTIAL SMOOTHING:
ONE OF
THE TWO WHEELER MANUFACTURING COMPANY EXPRIENCED IRREGULAR BUT USUALLY
INCREASING DEMAND FOR THREE PRODUCTS. THE DEMAND WAS FOUND TO BE 420 BIKES FOR
JUNE AND 440 BIKES FOR JULY. THEY USE A FORECASTING METHOD WHICH TAKES AVERAGE
OF PAST YEAR TO FORECAST FUTURE DEMAND. USING THE SIMPLE AVERAGE METHOD DEMAND
FORECAST FOR JUNE IS FOUND AS 320 BIKES (USE A SMOOTHING COEFFICIENT 0.7 TO
WEIGHT THE RECENT DEMAND MOST HEAVILY) AND FIND THE DEMAND FORECAST FOR AUGUST.
- REGRESSION
ANALYSIS METHOD: IN THIS METHOD, PAST DEMAND DATA IS USED TO ESTABLISH A
FUNCTIONAL RELATIONSHIP BETWEEN TWO VARIABLES. ONE VARIABLE IS KNOWN OR
ASSUMED TO BE KNOWN; AND USED TO FORECAST THE VALUE OF OTHER UNKNOWN
VARIABLE (I.E. DEMAND).
EXAMPLE 5
REGRESSION ANALYSIS:
FAREWELL
CORPORATION MANUFACTURES INTEGRATED CIRCUIT BOARDS (I.C BOARD) FOR ELECTRONICS
DEVICES. THE PLANNING DEPARTMENT KNOWS THAT THE SALES OF THEIR CLIENT GOODS
DEPENDS ON HOW MUCH THEY SPEND ON ADVERTISING, ON ACCOUNT OF WHICH THEY RECEIVE
IN ADVANCE OF EXPENDITURE. THE PLANNING DEPARTMENT WISH TO FIND OUT THE
RELATIONSHIP BETWEEN THEIR CLIENTS ADVERTISING AND SALES, SO AS TO FIND DEMAND
FOR I.C BOARD.
THE MONEY
SPEND BY THE CLIENT ON ADVERTISING AND SALES (IN DOLLAR) IS GIVEN FOR DIFFERENT
PERIODS IN FOLLOWING TABLE:
PERIOD(T)
|
ADVERTISING
(XT)
$(1,00,000)
|
SALES
(DT)
$(1,000.000)
|
DT2
|
XT2
|
XTDT
|
1
|
20
|
6
|
36
|
400
|
120
|
2
|
25
|
8
|
64
|
625
|
200
|
3
|
15
|
7
|
49
|
225
|
105
|
4
|
18
|
7
|
49
|
324
|
126
|
5
|
22
|
8
|
64
|
484
|
176
|
6
|
25
|
9
|
81
|
625
|
225
|
7
|
27
|
10
|
100
|
729
|
270
|
8
|
23
|
7
|
49
|
529
|
161
|
9
|
16
|
6
|
36
|
256
|
96
|
10
|
20
|
8
|
64
|
400
|
120
|
|
211
|
76
|
592
|
4597
|
1599
|
ERROR IN FORECASTING
ERROR IN
FORECASTING IS NOTHING BUT THE NUMERIC DIFFERENCE IN THE FORECASTED DEMAND AND
ACTUAL DEMAND.
MAD (MEAN
ABSOLUTE DEVIATION) AND BIAS
ARE TWO MEASURES THAT ARE USED TO ASSESS THE ACCURACY
OF THE FORECASTED DEMAND. IT MAY BE NOTED THAT MAD EXPRESSES THE MAGNITUDE BUT
NOT THE DIRECTION OF THE ERROR.
REFERENCES: - www.nptel.iitm.ac.in/
Comments
Post a Comment