When measuring personalization, it is important to eliminate background noise. In this context, one type of background noise is the carry-over effect. The carry-over effect can be defined as follows: when a user performs a search and follow it with a subsequent search, the results of the second search is influenced by the first search. A noteworthy point is that the top-ranked URLs are less likely to change based on personalization, with most personalization occurring at the lower ranks. This is a style of personalization based on recent search history, but it is not a consistent element of personalization because the phenomenon times out after 10 minutes, according to the researchers.
