Delays come in four basic “flavors”: physical, transactional, informational, and perceptual. Physical delays represent the amount of time it takes for actual “stuff” to move from one place to the other or to change from one state to another; for example, shipping products from the warehouse to retailers, or converting raw materials into useful products. Every transaction also takes time to complete, whether it’s a phone call or a series of contract negotiations—these can be called transactional delays. Then there are the delays associated with communicating information about the physical changes or decisions that have been made. Even with all our modern, high-speed communications systems, informational delays can still be quite long, because transmission does not necessarily equal communication. (That is, just because information was sent does not mean it was received and understood accurately.) The fourth source of delay is often the trickiest— delays in perception. The physical changes have taken place (after a delay), decisions have been made, and the information about the change has been communicated. But, our beliefs and assumptions are often so deep that even if the reality on which they are based changes, our perceptions don’t necessarily shift as easily. (It takes a long time to teach an old dog new tricks!)

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    These four kinds of delays are neither good nor bad; it’s how we handle them that determines whether they’ll cause trouble. In our rush to get things done quickly, we tend to underestimate the true delays in the system or even ignore them. But, delays are important to notice, because they can make a system’s behavior unpredictable and confound our efforts to produce the results we want, as we will see in the next section.