At AtTask, Scott Johnson says, milestones are weeks apart rather than months or calendar quarters. "Bite off a small piece, get it in someone's hands and start taking feedback," he advises.

"Discrete" means that each milestone is unambiguously defined in measurable terms with a solid deliverable. Jim Johnson prefers the term "stepping stone" to milestone. "At the end of a stepping stone you get a concrete result; a milestone might be more nebulous."

"Soft" milestones, such as percentage of overall completion, are notoriously troublesome because it can be hard to be sure the milestones have actually been met. Even worse are milestones based on effort expended rather than results. The classic example is measuring progress in terms of lines of code written.

Scope changes (also known as the "Microsoft Mambo")
One common method of trying to shore up a failing project is to start changing the scope. The manager or participants may scale back or eliminate features, especially if the changes don't involve actually cancelling requirements. This generally starts with relaxing requirements (such as response time) in an effort to reduce the development effort or to keep from discarding a problem module.

Requirements changes, per se, aren't a bad thing. In fact, they're pretty much expected in the agile method because of the constant user feedback the process produces. Indeed, changing the requirements can be a healthy thing.

The questions are which requirements are changing and why. The answers can tell you a lot about the health of the project.

And Finally. . .
Keep in mind that these signs are exactly that: signs. They don't mean the project has failed, or is about to fail. As AtTask's Scott Johnson points out, every "project experiences dips and gains," and you have to allow for them.

However, the signs may indicate the project needs closer attention from higher up the management chain. One useful rule of thumb for managers is to wait until at least two (short) review periods show problems before you do anything except watching closely.