  In Interactive IR, researchers consider the user behaviour towards systems
and search tasks in order to adapt search results and to improve the search
experience of users. Analysing the users' past interactions with the system is
one typical approach. In this paper, we analyse the user behaviour in retrieval
sessions towards Marcia Bates' search stratagems such as Footnote Chasing,
Citation Searching, Keyword Searching, Author Searching and Journal Run in a
real-life academic search engine. In fact, search stratagems represent
high-level search behaviour as the users go beyond simple execution of queries
and investigate more of the system functionalities. We performed analyses of
these five search stratagems using two datasets extracted from the social
sciences search engine sowiport. A specific focus was the detection of the
search phase and frequency of the usage of these stratagems. In addition, we
explored the impact of these stratagems on the whole search process
performance. We addressed mainly the usage patterns' observation of the
stratagems, their impact on the conduct of retrieval sessions and explore
whether they are used similarly in both datasets. From the observation and
metrics proposed, we can conclude that the utilisation of search stratagems in
real retrieval sessions leads to an improvement of the precision in terms of
positive interactions. However, the difference is that Footnote Chasing,
Citation Searching and Journal Run appear mostly at the end of a session while
Keyword and Author Searching appear typically at the beginning. Thus, we can
conclude from the log analysis that the improvement of search functionalities
including personalisation and/or recommendation could be achieved by
considering references, citations, and journals in the ranking process.
