Comments on: CCEVM Evaporating Cloud Diagram

By: Shankar

Shankar — Fri, 02 Jul 2010 19:20:20 +0000

By using EVM you are getting back into the cost world.
look and the cause and effect.
If there is a project overrun its usually because of an unresolved problem executing a task which is thrown up by buffer penetration.
The causes could also be unknowns in the more complex environment of research.
Boyth issues are addressed by the culture built into the CCPM implementation process and the rules that are to be followed.
While EVM may be the current way its only going to mislead yuo.

Shankar Rao

By: Glen B. Alleman

Glen B. Alleman — Thu, 19 Feb 2009 05:02:37 +0000

All,
The final concept on EV intensive programs is to assess the SPI on the critical path and the probabilistic critcal path. While Josh is correct in that all tasks (Gawd let’s hope you’re really at the Work package level of EV) impacts the agregated numbers, the the CP numbers that require management attention. Over/Unders on non-CP elements are interesting to bean counters. The PM (Program Manager) wants to know if we’ll make the delivery date – launch dates are booked 18 to 24 months ahead. MR hold back can cover the standard deviation values of CPI.

By: Glen B. Alleman

Glen B. Alleman — Thu, 19 Feb 2009 05:02:00 +0000

By: Glen B. Alleman

Glen B. Alleman — Thu, 19 Feb 2009 04:59:33 +0000

All combining CC and EV is common on IMP/IMS based programs. The CC aspects – buffer size – are derived from the Monte Carlo simulation of the needed “protection” for the deliverable date.
On a recent program the EV reports are stil used by Finance and Business Ops, but the “margin errosion” is how the CAMs managed on a weekly basis. A Monday morning meeting review the physical percent complete from the previous week (spacecraft construction and test), and the margin errosion below the planned level for that point in the program became the center of discussion.
As well Late Start/Late Finish reports and a thing called “bow wave” was used to guide that week’s work to “get to green” for the month end CPR.

By: Glen B. Alleman

Glen B. Alleman — Thu, 19 Feb 2009 04:59:00 +0000

By: Glen B. Alleman

Glen B. Alleman — Thu, 19 Feb 2009 04:55:56 +0000

Bill,
Your description of working out of sequence was common practice in many domains. Josh is NOT wrong in describing these activties. Cost “gaming” is done in many places when subcontarcting of non-interdependent workpackages are used. I’ve experienced them persoannely in the DOE and used them to short term advantage myself. A Work Authroization System is mandatory on any credible EVM program. DOE mandates this in DOE 413.3 as does NASA.
The size of the variance must pierce the reporting barrier for questions to be asked. It would be unheard of to have no variance on a monthly CPR or NASA 533M, so “If your management is willing to accept positive variances as evidence of “goodness” without asking for an explanation,” needs a clear and concise domain and context explination to be of any use to the PP&C staff. By this I mean positive and negative variances are common occurances. It’s when they pierce the planned variance boundary – usually forecast from the previous perid – that review is needed.
The current EVMS System Descriptions found in DCMA audited sites prohibits the performance of out of seqeunce work. Performing such work creates unfavorable indicies in two ways:
1. ACWP is applied to zero budgets – no BCWP for the ACWP to go against
2. BCWP is applied to unopened work packages again creating unfavorable indicies

Nearly every DCMA EVMS System Description I have seen, worked with, or written prehibits such behavior.

As a final note, rolling up an individual task’s EV to the performance report is rarely done. Work Package EV is usually all that goes to the finance system. At the task level every firm we’ve worked with uses 0/100, 50/50, or apportioned milestones. The common cost system CostView defines and restricts this usage. In one major prime contractor no other performance measures are allowed. Most certaintly some incremental BCWP provided by the CAM.
At the WP level the individual tasks are aggregated and weighted to produce the BCWP. SPI is reported on the schedule side and CPI catches up usuall one reporting period later.