A new study, “Google Scholar and DSpace”

“The average indexing ratio [in Google Scholar] for our sample of 10 recent DSpace repositories is 64.8%”

I wonder if the interface presentation has an influence? http://circle.ubc.ca/ is totally hardcore in presentation and keywording, and is indexed at 99%. Whereas http://dash.harvard.edu/ has a more student-friendly blog-like look and feel to it, and is indexed at just 26% despite the harvard.edu domain. But perhaps not, as I guess its more likely due to the presence or otherwise of good machine-readable metadata.