When looking at a change process it is tempting to see it as a single process, one size fits all, i.e all changes can be treated identically. However life is never that simple because changes have multiple facets. As well as identifying which change process needs to be followed, change dimensions provide information to assist us in prioritising work.
The most obvious difference, and the one that most people first come across, is the budget difference. Depending on who is paying for an change (IT or customers) has a direct bearing on the approval process. If the customer is paying (either directly or indirectly) then they, or their delegate such as the marketing department, must be involved in the financial approval to spend money. If it's 'free' then the customer involvement may be limited to status updates.
A second dimension is size. The larger the size of the change the greater the process complexity and check points. How do we measure size? A variety of metrics need to be used, typically financial cost to implement, architectural impact on the software system, impact on other systems, how many project owners/stakeholders exist (this increases the issues involved in communication and resolving conflicting needs). This concept is reflected in the ITIL change process which recognises three levels of change impact and has different process flows accordingly.
A variation on the 'financial cost to implement' value is that different software systems may have different costs to deliver a similar level of business value. So a legacy application that contains a lot of cruft might cost $x to deliver y benefit, however in a different part of the business a different system might take a lot less than x dollars to deliver the same amount of value. So when comparing changes in a priority list, looking at a pure financial cost may not be enough.
The third Dimensions of change can be considered as political, i.e. who is sponsoring or controlling our changes? Often the executive team are able to generate a significant amount of strategic work which could absorb the all potential development and related resources. However an organisation also needs to exist on a daily tactical level and there are significant improvements to be made by implementing as many improvements to the current business as possible. However these changes often appear less significant to executive sponsors because of their more tactical nature despite their possibly huge business value.
When the various facets of a change are taken into account we can then make some decisions about the change e.g. Who will make the change, what level of process maturity will the change need to follow, which budget will pay for the change, who will be involved in acceptance testing, when will the change be released and so on.
Next time I will discuss some practical consequences of this and how to avoid some of the resulting pitfalls