## How to Measure User Interface Efficiency

My frustration level reached a peak while using a mobile phone.  So, again, I’m thinking about GUI design.  Why are the interfaces so bad and how to fix them?

First step is just figuring out how to measure the badness.  There are plenty of UI measures out there and many papers on the subject.  BTW, I’m just a developer grunt, coding eight hours a day, so this is out of my league.  Yet, the thoughts are in my head so ….

To get to a goal takes work.  In physics, W = Fd.  Work equals force times distance.  No direct correlation to user interface.  But, what if W is equal to user interface element activated times number of possible objects to act upon, i.e., W = U x O.  Work equals UI force times number of options.  This ‘force’ is not a physical force or pressure, of course.  It is a constant mathematical value.

Example, you click on a button and then you are confronted with a choice of five options.  Lets say you are reading a web page and you want to share it with someone.  This takes too much work, way too much.  Even getting to the sharing choice is monstrous; click the menu button, click share, find which method of sharing, get to contacts app, blah blah.

So, here is what we have.  Activating a user interface element is a force; each type of element is given a constant value, a button is 10, a scroll bar is 100, and so forth.   The number of options that results and is relevant toward the end goal is the ‘distance’.

Now you divide this resulting value by how much time it took you to get there and you have Power.   P = (U x O)/T. (Update 7/26/2013: Probably a better dimension is actual distance of pointer movement or manipulations).

Add these up for each step in completing the goal and you have a metric for an interface user story.

Why use the number of options for distance?  The number of options presented to the user is stress. Kind of related to Hick’s Law, “The time to make a decision is a function of the possible choices he or she has”. If computers and software were not in the 1960s (face it modern stuff is just fancy screens) they would know what the hell I want to do.

A follow up post will give the solution to this User Experience Design (UXD) or Interaction Design (IxD) problem, and the solution is actually pretty easy.

Update

Created the follow up:  Proactive Interface

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