When splitting user stories it can be a daunting task to get Agile teams to conform to INVEST.
At some point, teams either struggle to abide by INVEST or they've hit the ceiling and are unsure of what to do next.
In either case, SPIDR may be the next step.
The concept comes from Mike Cohn (www.mountaingoatsoftware.com). The idea is not to necessarily replace INVEST. In fact, you can think of it as an addendum to INVEST or you can think of INVEST as an addendum to SPIDR. It really doesn't matter what order the Agile teams choose to apply the concepts.
We're all familiar with spikes and sometimes it makes sense to take a story and time-box it as a spike instead of applying story points. However, in some cases it may be more applicable to spike part of the story and perform the remainder of the story in a future iteration.
Using visual aids like a process flow chart can help teams to understand the work they're undertaking. Once the flow chart is established, teams can take a sequence of steps or take a really big step and turn it into a story.
Agile teams often struggle with vertical slicing. Thinking of interfaces instead may help the teams in splitting their stories. This may result in additional interface stories which essentially represents vertical slices. This type of splitting makes the work more manageable and more testable.
Grouping data is another great way of splitting stories. When getting started with this technique it may help to focus on the data groups that are high risk and provide high value.
Business rules can be very complex. Taking on too many in one story is a trap that many teams are guilty of. Using this technique adds a layer of transparency and can highlight the effort of something that may seem trivial at first. This transparency could result in a reduction of scope once the Product Owner and Stakeholders understand what is involved.
For more information on SPIDR, Mike Cohn provides video training at www.betteruserstories.com.