What you see depends on where you sit: The effect of geographical location on web-searching for systematic reviews: A case study.

There is limited guidance on how to web-search in systematic reviews and concern relates to the reproducibility of searches using search engines such as Google. The aim of this paper is to address one potential source of variation in Google searches: does the geographical location of a researcher affect Google search returns? Using a virtual private network, we ran the same web-search for the medical technology Dasatinib in 12 different countries. Two researchers independently extracted the search returns by country organised by page rank. We compared: C1. any difference in the items returned by Google searches between countries and C2. any difference in the page rank of items returned between countries. Searches were undertaken on Monday September 28th 2020. From 12 countries, 43 items were identified. For C1: 19 items were common to all 12 countries. Twenty-four items were missed by searches in some countries. This means that there were differences in search returns between countries. For C2: a randomised trial reported by Raddich et al was the first search return for all countries. All other items, common to all countries, varied in their page-rank. We find that geographic location would appear to influence Google search returns based on the findings of this case study. The findings suggest that recording the location of the researcher undertaking web-searching may now be an important factor to report alongside detail on steps taken to minimise personalisation of web-searches covered by recent guidance. This finding also has implications for stopping-rules.