Ask Eric: Questions & Answers

July 28, 2008 – submitted by Nikoletta Pehlivanos of California, USA

Question: What is the ratio of IVR Handle Rate to Menu Depth / Length? In other words, if one were to decrease menu depth, then what would be the numerical value of more callers staying in IVR (and not abandoning their call or pressing "0" to transfer to a CSR)?

Eric's response: You may have seen the depth vs. breath research on graphical interfaces. This shows that we are better off with more choices on a menu (18-24, in groups of no more then 10). This research does NOT apply to IVR. The problem with IVR is that you are relying far more on the user's short term memory.

In a voice interface you can not easily scan back to check a forgotten item or gain context. In a voice system you will have to limit your number of choices per menu to about five. Go much higher and users will get confused, lost, and hit the much feared '0'.

This said, fewer levels of menu is of course a good thing. At each additional level you will lose some customers. But there is no generic metric of the number that will be lost. This depends on the design of the interaction, as well as motivational factors. We have even found marked cultural differences in the tendency of customers to expect direct human support.

April 2, 2008 – submitted by Surendran Govindan of India

Question: I am designing a mobile application and wanted to know what are all the usability points to be considered. I am very new to the subject.

Eric's response: Well I can tell you are a bit new to the subject. I've been working on that question for over 30 years and I don't know all the points to consider. If this is an important application, please seek professional assistance. It does not matter how intelligent and well-meaning you are. It does not matter if you can speed read. It does not even matter if you have degrees in design or psychology. You won't get anywhere close to understanding how to design the user interface aspect of a mobile device in less then a year.

February 19, 2008 – submitted by Dee Ekmekjian of PA, USA

Question: CI understand that print advertising is geared toward people at a 5th grade reading level (in general). UCD includes a persona profile exercise which should help you understand your user types. But what about the content on the pages? Is there research that shows what the reading level of Internet users should be? Sometimes it's a no-brainer if your users all have the same educational background (say doctors or lawyers for example) but obviously that's not always the case. Please let me know if you have any research on this, or can point me in the right direction.

Eric's response: So your confusion is probably because you are thinking that you will write content for the average user.

Imagine you are building a doorway. The AVERAGE person (including children) might be 4 feet tall. So can you design the door to be 4 feet tall? NO! By definition about half the people will bang their heads on it. This is the same thing with writing. If you write for the average user, half the people will bang their heads on it. We write for the 5th percentile user (roughly). So if your average person reads at 11th grade level, you would probably be writing for 5th grade level to accommodate 95 percent of the population.

It is important to have some idea of the user population's reading grade level. This will vary depending on the type of site. A site for physicians will be different then a site for consumers.