The Difficulty of Comparisons

Comparing information about two or more options is a much more difficult task than simply finding information about each of the options, and most sites are not designed to help users perform such comparisons.

Strategies used by individuals asked to compare products:

A behavior seen frequently was "pogo-sticking" - where users would start from a menu, navigate down, jump back to the menu, navigate back to the next option, then back to the menu, etc. - was common, even where sites provided links among pages with similar products.

Spool's remarks about the pogo-stick behavior are neutral, though a number of other sources have cited this study to that it is undesirable behavior that site designers should attempt to overcome. Seems clear to me that the implication is that users are going to behave this way, even if links are provided to navigate horizontally, and there's nothing that can be done to discourage it.

Some sites provide options that enable users to do comparisons on a single screen - such as travel sites showing several flights in a timetable. This was deemed useful, but in some instances, users were distrustful (they felt that the options were presented in a manner to steer them to the one that was most profitable for the vendor to sell).

They also point to an example of the "decision engine" that allows users to answer a few basic questions about their needs, then shows them a table of options that best suit their needs. The author suggests that this seems helpful, but admits that "we haven't tested this, so we don't know if it actually helps."