There are multiple ways you could do this, but it will depend on how you plan to use the data, and what data sources you have to collect employee time.
The first question would be whether you are looking for the cumulative impact to the critical path or the total cost of lost time. If your end date slid, that can impact when you start generating revenue, and decrease your NPV. Calculating the time lost in calendar days be done by comparing versions of your schedules over time, provided you maintained that information.
If you are adding up delays that occur in parallel to find the total lost hours, you may be able to use actual charging data, or you may have to estimate it. Some charging practices and systems will separate out the time spent working the program, vs overhead waiting or doing other things. If the charging is all to the same budget, then you might try to compare the budget estimates vs. actual spending. You might have to ask the various teams to estimate the time lost, but then you must be careful about how you request the information. Are you looking for lost time by team, by issue, or the whole total regardless of who and why?
That is why when I build estimates for just about anything, I try to ensure I understand how they will be used so that I can try to collect the data in a way that fits the purpose. Other potential ways may waste time collecting data you don't need, change the accuracy of your results, or lack the detail necessary to analyze for the necessary business decisions. Saving Changes...
Stéphane ParentSelf Employed / Semi-retired| Leader MakerPrince Edward Island, Canada
Sometimes you don't lose time when managing issues to their resolution. But you most certainly will lose money.
Typically, you have a finite pool of people who can work on issues' resolution. These people will likely already have project tasks for which they are responsible. If you are lucky, the team members will be able to resolve issues, without affecting their task deadlines. There may be no slip in your project schedule but you will have to monitor that issue resolution time is not taking a bite out of your budget. (We don't typically build that time in our schedules or budgets.) Saving Changes...
Peter RapinSubject Matter Expect; Project Delivery| Independent ConsultantOntario, Canada
You talk of time lost - what about time gained, use of available float, opportunity to recover, re-establishing the critical path, etc.?
I would think that maintaining the critical path schedule and looking at the net delivery time difference at any point in time is the answer Saving Changes...
