Building from Bottom to Top
These five planesstrategy, scope, structure, skeleton, and surfaceprovide a conceptual framework for talking about user experience problems and the tools we use to solve them.
On each plane, the issues we must deal with become a little less abstract and a little more concrete. On the lowest plane, we are not concerned with the final shape of the site at allwe only care about how the site will fit into our strategy (while meeting the needs of our users). On the highest plane, we are only concerned with the most concrete details of the appearance of the site. Plane by plane, the decisions we have to make become a little more specific and involve finer levels of detail.
Each plane is dependent on the planes below it. So, the surface depends on the skeleton, which depends on the structure, which depends on the scope, which depends on the strategy. When the choices we make don't align with those above and below, projects often derail, deadlines are missed, and costs begin to skyrocket as the development team tries to piece together components that don't naturally fit. Even worse, when the site finally does launch, the users will hate it. This dependence means that decisions on the strategy plane will have a sort of "ripple effect" all the way up the chain. Conversely, the choices available to us on each plane are constrained by the decisions we make about issues on the planes below it.
Figure 2.7 The choices you make on each plane affect the choices available to you on the next plane above it.
Figure 2.8 This ripple effect means that choosing an "out of bounds" option on an upper plane will require rethinking decisions on lower planes.
That does not mean, however, that every decision about the lower plane must be made before the upper plane can be addressed. Dependencies run in both directions, with decisions made on upper planes sometimes forcing a reevaluation (or an evaluation made for the first time!) of decisions on lower planes. At each level, we make decisions according to what the competition is doing, industry best practices, and plain old common sense. These decisions can have a ripple effect in both directions.
If you consider your decisions on lower planes to be set in stone before you take on your decisions on higher planes, you will almost certainly be throwing your project schedule at the very leastand possibly the success of your final productinto jeopardy.
Instead, you should plan your project so that work on any plane cannot finish before work on lower planes has finished. The important consideration here is not to build the roof of the house before we know the shape of its foundation.
Figure 2.9 Requiring work on each plane to finish before work on the next can start leads to unsatisfactory results for you and your users.
Figure 2.10 A better approach is to have work on each plane finish before work on the next can finish.