There are good practical reasons for using AgileESM©. The Schedule Performance Index for time that is used by AgileESM© accurately measures and tracks time performance throughout a project’s life cycle. AgileESM© also adds value to common Agile tools such as burn charts. It assesses the time earned on a project and not just the number of release points completed or remaining.
Practicality, however, does not prove validity. Why does the validity of AgileESM© need to be proven? Why is the practice not enough?
Practice is a matter of experience, and within the Agile community, there is experience that runs counter to AgileESM© practice. Consider the following statement:
Artificial measures such as EVM [Earned Value Management] typically prove to be overhead at best, whose only value is to cater to the dysfunctional bureaucrats infesting many organizations. (Scott Ambler, FullText).
Maybe Scott is being intentionally provocative. Certainly, his statement has evoked strong responses. Consider this one:
Scott makes several fundamental errors in [his] discussion. … [You should] ignore arguments against EV[M] from those [who have] not … deployed it successfully. You wouldn't take agile advice from someone who has not successfully deployed agile in a domain and context similar to yours. Don't do the same for anything else. (Glen B. Alleman, FullText).
Both views are based on experience, and experience, although valuable, is not conclusive proof. Rather than countering one subjective claim with another, we need a more objective approach. If EVM metrics can be mathematically derived from Agile metrics, there is an objective reason to accept their validity for Agile projects.
That is precisely what has been done. EVM cost metrics have been deduced from Agile metrics. Click here to see the derivation. And, now, AgileESM© metrics have been deduced from Agile metrics. Click here to see the full proof. An outline of that proof is included in The Proof section of this web site.