Deckungsbeitrag Paradigm

**Yes.** The contribution-margin philosophy (especially multi-stage *Deckungsbeitragsrechnung*) is a core part of German-speaking management accounting and is widely taught and applied in retail controlling across the DACH region (Germany, Austria, Switzerland) and much of continental Europe.

Here are the most relevant textbooks and academic sources:

### Foundational / Classic Textbooks

- **Paul Riebel** – *Einzelkosten- und Deckungsbeitragsrechnung* (multiple editions, originally 1950s–1990s, later reprints).  

  This is the seminal work on *relative Einzelkostenrechnung* (relative direct costing). Riebel rejected arbitrary allocation of fixed/common costs and insisted on only assigning costs that truly disappear if a decision object (product, customer, order, etc.) is dropped. His approach is the theoretical backbone of rigorous contribution-margin thinking in German accounting.

- **Wolfgang Kilger** (later editions with Jochen R. Pampel, Kurt Vikas and others) – *Flexible Plankostenrechnung und Deckungsbeitragsrechnung*.  

  The standard university and practitioner textbook on flexible standard costing combined with contribution-margin accounting. It is one of the most influential cost-accounting books in the German-speaking world and explicitly treats multi-stage contribution margins (*mehrstufige Deckungsbeitragsrechnung*) as the primary tool for short-term decisions (pricing, product mix, make-or-buy, etc.).

### Retail-Specific Sources

- **Jörg Becker & Axel Winkelmann** – *Handelscontrolling* (several editions, Springer).  

  The leading German textbook on retail controlling. It discusses contribution margins, Direct Product Profitability (DPP / *Direkte Produktrentabilität*), assortment and category decisions, and the practical difficulties of allocating fixed costs (space, personnel, etc.) in retail. Contribution-oriented metrics are treated as central for operational decisions.

- Academic work on **Sortimentscontrolling / Category Management** in food and non-food retail (e.g., papers by Hendrik Schröder and colleagues). These frequently apply multi-stage contribution-margin schemes or Riebel-style relative direct costing to assortment, shelf-space and customer profitability decisions. One example is work on customer-related contribution accounting in multi-channel retail that explicitly references Riebel’s principles.

### Broader Context

German cost-accounting tradition (often called *Grenzplankostenrechnung* or contribution-based approaches) places much stronger emphasis on separating variable/direct costs from fixed/common costs for decision-making than classic Anglo-American absorption (full) costing. Surveys and comparative studies regularly note that German industrial and retail firms are more likely to use direct/contribution costing for operational decisions than their U.S. counterparts.

**Important nuance**: In real retail practice the pure textbook ideal is often mixed with pragmatic tools (DPP, space productivity, category contribution after allocated logistics/handling costs, etc.). Nevertheless, the *mindset* that absolute contribution (euros of margin that actually help cover fixed costs) matters more than percentage gross margin remains the dominant decision logic in most European retail controlling departments — exactly the distinction that leads to the €3 rather than the €2 answer in the original quiz.

If you want readable entry points in English, look for comparative papers on “German cost accounting” vs. U.S. systems or translations/summaries of Kilger’s and Riebel’s ideas; the full depth is still mostly in German-language literature.

-----

Goal a very scientific paper 

Abstract

This note argues that retail decision-making should be based on absolute contribution rather than average percentage margins. Percentage margins are useful for reporting, but they are misleading as operational targets because bills are paid in currency units, not ratios. A product or category can appear attractive on a percentage basis while still contributing too little in absolute terms to cover fixed costs, store expenses, and the economic value of scarce resources. From this perspective, contribution should be measured in money terms at the SKU level, where the relevant question is not whether an item “looks good” in percentage terms, but whether it leaves enough cash in the business. This logic also clarifies historical retail practice: before modern information systems, percentage-based shortcuts were often adopted because fine-grained product-level computation was difficult, not because it was theoretically superior.