<aside> đźš© The Cambridge Exclusion Calculator is an easy tool to use, to assess the HF capabilities of a given product or concept. This page describes how to use it to drive design.

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Overview

The Cambridge Exclusion Calculator (CEC) is a browser-based tool to assess how many people will be excluded from using a product or design, based on several human factor considerations.

In this course, the CEC will be used to identify problems with your design concepts, which in turn will help you improve your design.

Details on how to use the CEC are available on the CEC website.

This page will focus on how you can assess a Design Concept from a HF point of view, and develop Design Issues and Requirements from those assessments.

Driving Design with the CEC

General Process

Refer to the Section In Loop 2 of Human Factors Analysis for the general process to follow.

Example

Consider the case of changing the ink cartridge in a pen like a Cross Century ballpoint pen. The relevant features of the concept of this pen are:

  1. that the top of the pen is pulled off to change the cartridge;
  2. that the top of the pen is twisted clockwise/anti-clockwise to extend and withdraw the writing tip (thereby requiring sufficient friction with the pen’s internals to achieve this); and
  3. that the cartridge itself must be screwed in place to allow the rotational motion necessary to extend and withdraw the tip.

The Situated Use Case for this example can be summarized as: The Persona wants to change the cartridge of their pen after dinner one evening at their desk at home.

You can watch this YouTube video of how the cartridge is changed this kind of pen.

A reasonable subset of Usage Scenario steps for changing the cartridge might be as follows:

  1. Pull off the top of the pen.
  2. Unscrew the old cartridge.
  3. Withdraw the old cartridge.
  4. Pick up the new cartridge.
  5. Insert the new cartridge.
  6. Screw the new cartridge in securely.
  7. Push the top back on the pen.

If we were to apply the CEC to this case, we might develop the following inputs to the CEC.

<aside> ⚠️ NOTE: be sure the set the correct genders and age groups at the top of the CEC page.

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Inputs for Vision

Considering the US steps, we determine that the most challenging visual step is Step 5, because the cartridge is quite thin, and so is the hole in the body of the pen into which the cartridge must be inserted. Thus, the user would have to have sufficient vision acuity to properly align the cartridge with the hole.

We also determine that this step will be roughly equivalent to being able to read “ordinary newspaper print” in the CEC, because the diameter of the cartridge and of the hole are roughly the size of ordinary newspaper print.