21 June 2019

How vital are the wireframes or designed UI files for a good project development estimate?

We’re all the time forced to make a ton of business ot tech decisions about logic or about features to-be-released in the apps. All that has great impact on project costs and time estimates.

A feeling of not knowing something, or knowing something to higher or lower degree is pretty familiar for those who work in the web development for long. And this feeling becomes the strongest when estimate questions arise.

Custom development projects are associated with high uncertainty level that gets decreased over the course of the project. It’s true, that uncertainty in the estimate is caused by the uncertainty around how exactly requested challenges will be resolved. As we progress with the project and make decisions, we reduce associated uncertainty and know about wanted result more and more. But estimates are wanted at the beginning of the project, not after. How to deal with high level of uncertainty and still provide accurate and useful estimates?

Researchers in their studies made conclusion that project estimates can be a subject to a predictable level of uncertainty at every known stage of the standard web development project. The following concept has been introduced to visualize this statement: the Cone of Uncertainty.


The Cone of Uncertainty shows how estimates become more accurate as a project progresses. But, as it’s been mentioned, accurate estimates are wanted in the beginning of the project, not when they are already closed and software has been complete.

The solution to common estimation challenge would be to move through the Cone as quickly as possible and keep in mind the error factor. For developers it means that when doing the estimate of an initial concept, the range should be high enough to highlight the level of being uncertain.

Wireframes, sketches or fully designed and approved mockups play significant role in reducing error factor and allowing all involved parties obtain more useful and more reliable estimation.

So, when development team gets quote request on a stage of initial concept in a format like:

- Simple UI like tables and content inside on each page;
- The search field for quick access to the info;
- The edit and delete functionality for all rows of the tables;
- The functional of exporting content to offline document.

… its estimate can be a subject to 4x error factor.

But when development team gets a wireframe, they can reduce this error factor to 0.8x — 1.25x and provide more accurate quote.


Are there any tools that incorporated this concept into the estimation process?

One of the examples: estimatess.io tool. For proper estimation it requires project wireframes, sketches or design files. Developer can note required functional looking at approved UI and define more accurate efforts estimates, in comparison to looking at written specification file.


Instead of a summary:

1. Consider the effect of the Cone of Uncertainty on the accuracy of your estimate. Your estimate cannot have more accuracy than is possible at your project’s current position within the Cone.
2. Moving forward through the Cone and doing estimation based on visual materials (approved UI, website wireframes, designed sketches) allows reducing the estimate error and get more useful estimate.

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