It’s great to have internal competition between your products. And Skype has it between SkypeToGo and the iPhone version for some functions. The question then becomes, which of the two do I use, while still giving money to Skype. I don’t need to look for external things.

I use SkypeToGo a lot for international calls. When Skype for iPhone came out, I was curious to see how it compares with SkypeToGo, with my hypothesis being that Skype for iPhone is slower. So I did an analysis using the Keystroke-Level Model. It’s one of the more “hard science” parts of Human-Computer Interaction methods. I won’t write the theory here, you can read more in Wikipedia or see the project page.

In short, there is a software called CogTool that neatly packages up the hard science. You give it the system interface, describe what keys the user presses, and it tells you how long the actions are going to take. There’s science behind why the numbers it reports are correct. Go read the papers if you want to learn more.

So, long story short, I compared SkypeToGo and Skype for iPhone for the task of calling a phone number that was in my contact/shortcut list. I had previously set up everything with all sorts of auto-logins. So I am answering the question, “starting from the iPhone home screen, how long is it going to take me to be connected to phone number X?”

These were my preliminary results.

In short, CogTool told me that the task takes 8 seconds with SkypeToGo, and 6.6 seconds with Skype for iPhone.