Blog posts in English

An illustration of the resource vs coverage problem

The illustration below is taken from an old book, I’m reading (*):
Illustration from: Holger Paaskesen: Vi lærer for livet?
Fig. 3 shows a desert land which will be cultivated by irrigation, i.e. the artificial application of water. Fig. 4 shows the amount of fertile soil available. Now, the farmer can decide to spread the soil all over the area, by which the layer of fertile soil will be so thin that nothing will grow in any part of the land. That is not a good plan and all the work involved will be fruitless.
But there’s an alternative: The soil can be spread over a section of the land, for example the area marked in fig. 3. This way the layer of soil will be thick enough to ensure that there will be exuberant growth and good utilization in the smaller area. This is obviously a much better plan.
This scenario not only applies to farming: It illustrates a problem we often face in testing, where the amount of functionality being developed is much larger than the what we can cover in a decent way. It is my experience that it is always better to focus testing on sections of the system than to try to check everything: There will be areas of the system which will be left untested, but what you test, you will cover well.
As a decision maker, I’d much rather have in depth knowledge about parts of the system, than to know very little about everyting. It will give me much better foundation for making good business decisions.
*) The book is Holger Paaskesen: “Vi lærer for livet?”  from 1968. It’s English title would be “We learn for life?” and it’s a book about school education.

0 replies on “An illustration of the resource vs coverage problem”

An exception to this approach arises when things are connected. I can cover one part extensively and it may fail in a fascinating way once it is connected to the other parts I didn’t research.
As I look at it now, from the perspective of the current project, it is indeed beyond impossible to cover the entire ground. But if I focus on only one area I will lose the ability to reason about that part in the context of the system. Therefore I need to spread my attention. The fact that I’m spread ‘too thin’ should not keep me from exploring beyond the one part.

Hi Joris, that’s a very valid comment. Thank you for that one!
I guess we can say that the model I’m presenting here (let’s call it “the flat desert model”) is only valid when the structure of the system is “flat”. Many systems are indeed flat or monolithic, but you are right, there are some that aren’t. Integrated systems are never flat.
And for what it’s worth, desert areas aren’t flat either: Some parts of the desert are usually a bit more fertile than other parts, so another point could be that we should think (and explore) before we pick the one area to explore in depth.

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