Simple tool for shipping dates estimates without uncertainty

Question

What I'm looking for is very simple: I want a tool that computes the calculated, as opposed to estimated based on confidence intervals, shipping date given a list of tasks with total estimates and current progress each without introducing further uncertainty as I want to handle that externally.

I want it to take workdays duration and user input holidays into account, etc.

I know Fogbugz's Evidence Base Scheduling does something very close to that but I would like it without the statistical aspect and associated confidence intervals. I'm aware it's a drastic simplification and that statistical estimation is the essence of EBS but I'm not looking for a subjective discussion here, I just want to be able to access this simple information (the supposedly exact shipping date) at any given time during the project without having to calculate it myself.

So I'm looking for one of three things : 1) a way to customize Fogbugz (6.0) to show me the information I want besides confidence intervals 2) a way to customize Fogbugz to set estimates uncertainty to 0 3) another tool (free) that does what I want exactly.

EDIT: By "supposedly exact" or "calculated", I don't mean with respect to what is actually going to happen, that would indeed be trying to predict the future. I mean with respect to the information that was input, together with its obvious uncertainty. In that case, I guess estimates for individual tasks should be more seen as spending limits or upper bounds. The information I would like to be able to compute is really very simple : if everything goes exactly as specified, where does it take us ? Then, with information about how the estimates were made, such as the ability of each individual developper to make good estimates, I can derive the confidence interval. EBS does this automatically and, undoubtebly, very well which is why I use it. What I would like is to obtain is one more little piece of information, ie the same starting point EBS uses and try to play with my own asumptions as to how the statistical estimation should be made.

Answer 1

You can't predict the future. So any calculated shipping date can only be a guess. That guess depends on the confidence intervals around each individual number that went into it. This is a matter of definition -- even though you may not like it.

You may want to have a "100% confident" date, but such a thing (by definition) cannot exist. You cannot have an uncertainty of zero unless you want a date infinitely far in the future. It's the nature of statistics: the distribution is actually infinite, but data is considerably more likely to cluster around the mean.

The only thing you can do is pick a really big confidence interval (99.7%). You are free to ignore the supporting statistical facts about the confidence interval and pretend it has zero uncertainty. For all practical purposes 0.3% uncertainty is small enough that you're not going to be unhappy with that date.

However, all statistically-based predictions of the future must have uncertainty. It's a law.

Answer 2

http://en.wikipedia.org/wiki/Crystal_ball

Answer 3

FogBugz will show you the sum of estimates at the bottom of the LIST page, labelled "Total estimated time remaining". This is the raw sum of estimates, without any EBS calculations.