One suggestion is to run through a thought experiment with her. For example: Let's assume this is a project that will take about 6 months. Let's base the schedule on a 180 day time line. So you desire us to hit that 180 day target from six months away to within 5%. OK that's 0.05 * 180 = 9 days. Now is that a plus or minus 5% or a 5% range? Or in absolute terms for this example do I have to be within 171 - 189 days (+/-5%) or within 176 - 185 days (5%). So to continue this example, consider a team doing 2 week sprints. This would equate to 12 - 13 sprints with one sprint error.
|by Mountain Goat Software|
Mike Cohn created the web based interactive project success sliders shown above; described in the book Radical Project Management by Rob Thomsett.