Marissa Mayer on Quick Response Time

Google's Marissa Mayer told an audience at a Web 2.0 conference last week that quick response times are a critical - possibly the most important - contributor to usability. Response time is the amount of time it takes for a product to respond (provide useful results or feedback) to user requests. Slow response times lead to user frustration and less usage of your product.

For example:

In a survey on search, Google asked people how many results they would want by default; they responded that more is better, Mayer said. So the company conducted an experiment, providing some searchers with 30 default results. But it took, on average, a half-second longer to get those results than when the default was 10 results, she said. Out of frustration, people conducted fewer searches.

"This indicated extreme unhappiness," Mayer said. "It was clear that we weren't going to make this change."

A half-second increase in response time resulted in a large increase in frustration and consequent reduction in product usage.

The anecdote also supports the notion that giving customers what they say they want is not always a good idea. Sometimes, you can't know what people want until you observe what they actually do, and what they like, in a given situation.