In addition to cost planning and success planning, sales planning forms an essential part of the company's planning system. Due to the interdependence of sales, cost and success planning, the plan contents of the follow-up plans are usually determined by the preparation of a partial plan. Based on the company's market orientation and the resulting dominance of sales planning in the operational planning system, sales planning generally forms the starting point for all further operational sub-planning.
It is characteristic of sales planning that it makes statements about future sales volumes and values, which are derived from the laws of the past about the relationship between the forecast sales or sales and the influencing variables that determine them. The influencing variables of a company that determine sales are made up of macroeconomic and individual economic components. While macroeconomic influences on sales can result from the trend and economic development, from industry-related economic shifts and industry-related seasonal developments, company-specific influencing variables result from the use of marketing instruments.
If sales planning is to be used as a controlling instrument, it must first be determined to what extent the sector-related economic development fits into or deviates from the general economic development and which regularly recurring seasonal influences must be taken into account in the sales forecast. Then there is the recording of the individual company influences through the use of marketing instruments on sales, especially the Pricing policy, Advertising and quality policy as well as the Product policy of the company, ie the rhythm in which new products are introduced. Each product usually has a product life cycle (product life cycle concept) that can be planned individually and for the corresponding product group. A consideration of the company-specific influencing variables with regard to the turnover can be recorded with various statistical methods, e.g. with the help of the simple method of trend extrapolation, but its use only makes sense if no trend breaks are to be expected or with more precise, but time-consuming methods of Correlation and regression analysis that lead to the formation of indicator and explanatory models. While the indicator models do not assume a causal relationship, but rather only a "time-functional" relationship, the explanatory models are multi-level on a causal basis. On the basis of plausibility considerations, a number of influencing factors are first preselected from the multitude of assumed relationships, which are then tested with the help of a correlation calculation. In a further step, highly correlated influencing variables form the basis of the causal explanation with the help of regression analysis. In detail, the item or item group-related sales planning takes place in the following work steps:
1) Selection of the variables influencing sales: With the help of the correlation calculation, from the multitude of variables influencing sales, those factors (e.g. advertising expenditure, price level, range of products, price-performance ratio, life cycle of the products) as well as external variables (e.g. number of unemployed, national income, incoming orders in industry and seasonal fluctuations) that have an impact on the respective turnover.
2) Clarification of the temporal interdependencies: As a rule, it can be assumed that the interrelationships between sales and influencing variables are not uniformly on the same temporal level. Certain influencing factors work at the same time as the sales development. For other sizes there is a lead or lag. In order to clarify these temporal interdependencies, the correlations between the time series of the dependent variable sales and those of the independent variables must be calculated with a time shift for the periods in question.
3) Determination of the functional relationships between sales and sales-determining influencing factors: With the help of the regression calculation, the dependent variable y is recorded as a function of one or more independent variables x1, x2, ..., x ", so that laws between sales and sales-determining influencing variables are revealed.
4) Derivation of the forecast sales: After the influencing variables that determine sales for the respective forecast point in time have been determined and the values corresponding to the temporal relationship have been determined, these must be used in the corresponding regression functions in order to obtain the sales to be expected according to the regression normal line. In addition, the forecast must be carried out for all sales-relevant indicators in order to integrate the various influences on the sales to be forecast (multi-dimensional forecasting process).
5) The determination of the average forecast deviation: In the previous presentation, the forecast was determined as a single-valued arithmetic mean from the individual forecasts for the significant influencing variables. This concept needs to be modified, as the forecast turnover cannot be determined completely by the exclusively quantitative influencing variables taken into account, but can only be determined in ranges. The factors that are not explicitly taken into account as influencing variables in the approach mean that the actual sales do not correspond to the values on the “normal line”, but rather deviate upwards or downwards.
They are expressed in the fact that the actual sales are scattered within a range around the regression line. To determine the margin of deviation from the regression line, the average deviation between actual and forecast sales can be determined for the quarters or months on which the correlation and regression calculation is based, and the average deviation can be specified, e.g. in % of the forecast sales.
The article or article group-related sales values per time unit determined in the context of the sales estimate or forecast must be included in the time-dependent sales planning. As a condensed information instrument, the cumulative sales plan can be based on the article or article group-related individual forecasts or, if this degree of differentiation and accuracy is not available in the operational sales forecast, with corresponding "coarser" criteria according to article or customer groups, e.g. according to the ABC analysis, structure. The sales values are to be set up per month and as a cumulative value over the planning section (e.g. one year).