Demand Amplification and Information Sharing

Why it matters

While consumption at the final point of use varies only within limits, the orders going to the supplier can swing sharply up and down. Correcting stocks period by period, accumulating needs into a large lot, or adding a separate safeguard against the same uncertainty at every stage can widen this gap. Demand amplification is the visible name for this behavior. Even when total orders and total consumption are equal, the distribution across periods can be very different. The supplier may sit idle one week and then face demand beyond its capacity the next. Looking at the total quantity alone hides this change in load. The variance ratio is used to examine how large the fluctuation of orders is relative to the fluctuation of consumption over the same time span. Delay and stock results are evaluated separately.

Variance rests on the squares of the distances of the values from the mean. Large deviations carry more weight in this calculation; so it differs from simply comparing the highest and lowest quantity. Orders and consumption must be measured in the same unit and at the same period width. Dividing the variance of weekly orders by that of daily consumption can confuse the effect of time aggregation with demand amplification. Choosing different weeks, even for the same product, is misleading. Events such as a holiday, an inventory correction or a product change can affect the scope of the series. Before the calculation, the record boundary and the periods are matched. Not every division that can be computed numerically produces a meaningful measure. The comparability of the data comes before the calculation result.

Information sharing is not just sending more tables. Actual consumption, usable stock on hand, open orders and firmed needs must be separated from one another. If the supplier takes consumption information for a new order, the same need can be met twice. If the buyer shares only orders, fluctuation arising from stock correction can look like end-user demand. For this reason information is accompanied by a definition of authority: which record is for information and which is permission to produce or ship? At what moment does a change become binding? How is the old version closed? Shared visibility is useful only when these questions have a shared answer. Quickly shared information that is misread can cause more confusion than a slow but clear record.

The variance ratio is a starting point for diagnosis; by itself it is not proof of a cause or of good service. A low ratio does not guarantee that consumption is being met. It may be possible to reduce volatility by holding orders constant, but stock can run out when consumption is unexpected. A high ratio also does not mean only the buyer is at fault; the supplier's minimum lot or shipping calendar constraint may be accumulating the orders. Throughout the review, the order rule, the stock target, the delivery frequency and the actual service are handled together. The aim is not to force the measure's value down, but to protect availability while reducing unnecessary amplification. An information-sharing trial should therefore also include checking the stock and delivery results.

Formula