The first stage of mathematical modelling took a large number of companies with mature operational PMO functions and plotted their PMO headcount against the number of people they were supporting. For this first stage we assumed all variables regarding PMO functions were normalised (in the following pages we go into more detail regarding those variables and include weighting factors for each to allow you to drive a more detailed estimate).

The table below shows the non-linear correlation between these two variables:

TABLE 1

Programme Headcount	30	60	120	200	300	500	1000
PMO headcount	2	3	5	7	9	13	20

For the more mathematically minded amongst you the simplified model you can use is:

TABLE 2

PMO FTE = 1/5 (N2/3)

Where: PMO = Programme Management Office FTE = Full Time Equivalent N = the total headcount the PMO is supporting

You should calculate the estimate for your PMO as we will be using this later on in the article to create your more detailed estimate. This figure is a good first comparitor to your current PMO size. If the figures are wildly different (e.g. a different order of magnitude) you may find the following sections help explain some of that differential. The next stage is to understand the variables that will impact the size of your PMO...