# Time Estimation

I am preparing for the Project Management Professional exam offered by the Project Management Institute.  If I pass the 250 questions, I will be certified as a Project Manager.  It is quite a daunting test with lots of memorization of process names, knowledge area, inputs, tools and techniques and outputs to remember for the test.  The best way for me to learn these kinds of concepts is to apply to my every day life.  So here goes on one of the formulas that I need to remember.  In the knowledge area of project time management, there is a section devoted to estimating activity duration.  There is a formula called Beta Distribution or PERT (program evaluation and review technique) that I need to master and instantly recall.  The PERT formula goes like this:

tE=(tO +4tM + tP)/6

tM = most likely, this estimate is based on the duration of the activity given the resources likely to be assigned, their productivity, realistic expectations of availability for the activity, dependencies on other participants, and interruptions.

tO = optimistic, this activity duration based on analysis of the best-case scenario for the activity

tP – pessimistic, the activity duration based on the analysis of the worst-case scenario for the activity.

Let’s apply this to a real world example.

How long will it take me to write my next blog?

Most likely (based on my history of blogging posts, normal work week, normal activity levels) = 7 days

Optimistic (Few distractions, stumble on to something super interesting, high energy) = 3 days

Pessimistic (get sick, super busy at work, travel)= 12 days

tE = (3 + 4(7) +12) /6

tE = (3+24+12)/6

tE = 39/6

tE = 6.5 days

So, now when I get the PERT question, I will remember this post and it will come to me easily.  At least that is the plan.  See you again at this blog site in 6.5 days.  And thanks for letting me practice for the exam through blogging. Now onto work breakdown structure (WBS).