Tuesday 18 December 2018

Verification and control of Production Forecasting

A Production forecasting means to estimate the future demand for goods and services. It is an estimation of a wide range of future events, which affect the production of the organization.

An important step after forecasting verification is done is such a way that the data reflects the past and the underlying causes of system request. All representations of these reliable forecasting, forecasting results can continue to be use. If during the verification process found doubts the validity of the forecasting methods use, to look for other more suitable methods. Validity must be determine by the appropriate statistical test.

After a forecast is made, always arises a doubt does need to be made a new forecasting method. Forecasting should always be compared to actual requests on a regular basis. At one point the action to be taken when forecasting revision found evidence of a change in the pattern of demand that is convincing. In addition, it causes changes in the pattern of demand must be known.

Production forecasting Method

Adjustment method of forecasting is done immediately after the change in the pattern of demand is known. There are plenty of gadgets that can be use to verify the forecasting and detecting the cause of system change aspects influenced changes in patterns of demand. The simplest form is the map control forecasting, similar to map the control quality. The Map of this control can be create by the availability of data is minimal.

Map Moving Range

A map Moving Range design for comparing actual demand value with the value of forecasting. Actual demand data is view and compare to the value of forecasting at the same period. The map was developed into a period to come so data forecasting can be compared with the actual demand. During the basic period (a period at the time of calculating the forecasting), Moving Range use for verifying forecasting techniques and parameters. After forecasting method is specify. The map Moving Range use into testing the stability of the system causes that affect demand.

At the very least there should be 10 and preferably 20 data to create the map Moving Range. These limits are set such that there are only three of the expect 1000 point that is outside the boundaries of the control, if the system causes that behind it remains the same.

Single point for Production forecasting

If it finds a single point that is outside the boundaries of the control at the time the forecast is verify, it should be determine whether the data should be ignore or a new forecasting should be sought. If a point is outside the bounds of control should be investigate the cause. The findings may require extensive investigation.

If all points are within the boundary of, assume control of the resulting demand forecasting has been quite good. If there is a point that is outside the bounds of control means forecasting obtain and should be revise. Map of control can be use to find out if there is a change in the system which causes the request so it can be determine aspects influence the equation a more suitable new forecasting system causes that occur at this time.

Test Conditions Beyond the Control

The most conclusive Test for conditions beyond the control of is the point beyond control. In addition, there are also other trials with the same level of possibilities. The technique use here is design to be use with the minimal amount of data possible.

This test is done by dividing the map control into six parts with the same interval. Area A is the area outside the ± 2/3 (2.66 MR) = ± 1.77 MR. (above + 1.77 Mr. dan under – MR. 1.77). Area B is the area outside the ± 1/3 (2.66 MR) = ± 0.89 MR. (above + 0.89 Mr. dan under – MR. 0.89). Area C is the area above or below the mid line. Test condition out of control are:

  • From the three-point sequence, if there are two or more points is A?

  • Of the five successive points, whether there are four or more points that are locate in the area of B?

  • Whether there are eight consecutive points are in one of the sides (above or below the mid line).

Description of areas A, B, and C shown in the picture. The condition of the third when the above criteria are met is treat the same as the conditions of point is outside the boundaries of the control.

The use of the Moving Range for verification of forecasting

The use of the Moving Range to verify the results of the earlier example of forecasting. In such cases, if the map Moving Range denotes circumstances beyond the criteria of control data that does not come from the system the same result will be discard and forecasting functions specify again.

Examples of linear forecasting case previously use to describe the process of verification of forecasting. The calculations require to verify linear forecasting made shown in the table. Map of control shown in the picture. It can be seen there are the cause of the system is stable and can be express statistically that the valid linear forecasting.

One of the things important for activity planning and controlling production is demand forecasting is accurate and reliable. Because the request could not be predict accurately immediately, it takes certain methods which will point to the forecast is good. The forecasting method is a technique for predicting future scientifically, that will be better than forecast try.

Demand for Production forecasting

To make a good demand forecasting, it first needs to be foreseen environmental circumstances which affect the amount of demand for the products of a company. Forecasting the next environment use as the basis for forecasting industry. And then recently conduct demand forecasting the company's products.


In General, to estimate the demand in the foreseeable future, can use the six main forecasting methods: research interest buyers, salespeople, expert opinions, market testing, analysis, and time series analysis request statistics. These methods vary in terms of their compatibility with the purpose of forecasting, product types, as well as the availability and reliability of data own by the company.

It should be note that the accuracy of forecasting will be reduce in line with the increase of contraction interval of forecasting. Forecasting only revise if there is a change in the system causes which aspects influence demand.

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