Linear demand systems and quasi-linear quadratic utility models are widely used in industrial economics. We clarify the link between the two settings and explain their exact origin as it seems to be little known by practitioners. We offer practical recommendations to achieve consistency, tractability and a reasonable degree of generality when using the linear demand framework. We show that all tractable versions of the model used in practice are (almost) identical and have a mean-variance structure. We provide concise, ready-to-use formulae for the symmetric model. Finally, we revisit and extend the asymmetric model of Shubik and Levitan.

线性需求系统和准线性二次效用模型在工业经济学中被广泛使用。我们弄清楚这两种设置之间的联系，并解释它们的确切来源，因为从业者对此鲜为人知。我们提供实用的建议，以在使用线性需求框架时实现一致性，易处理性和合理的通用性。我们证明，在实践中使用的模型的所有易处理的版本（几乎）都是相同的，并且具有均值-方差结构。我们为对称模型提供了简洁易用的公式。最后，我们回顾并扩展了Shubik和Levitan的不对称模型。