> However management often confuses precision for accuracy One of the best tools for estimation, I've discovered, is not an estimation technique at all, but a

> However management often confuses precision for accuracy One of the best tools for estimation, I've discovered, is not an estimation technique at all, but a communication technique: Build error bars into your estimates when you deliver them. My preferred way is to give 30/60/90 estimates: I'm 30% confident it'll be done in 20 hours, 60% confident it'll be done in 45 hours, and 90% confident it'll be done in 60 hours. Deliver estimates thusly to management and they can determine how safe they want to be. If they say "great, we'll plan on 45 hours," remind them that there's nearly even odds you don't hit that. If they complain that the range is too wide ("how can it be 20-60 hours?! I need more confidence!") then you can use that as justification for exercises which increase confidence (prototyping, more detailed planning, research around any unknown systems, etc). The exact format doesn't matter - maybe you prefer to give ranges or standard deviations or what-have-you - the important thing is to make it impossible for someone receiving your estimate to ignore the uncertainty in the numbers you give.