David McKenzie and Berk Ozler are running a scientific study, and start with the impact on paper downloads.
To place the impacts in perspective, it is useful to first compare them to the download and abstract numbers for an average NBER working paper: 10.3 abstract views per month and 4.2 downloads per month from Repec in months 3-14 after release.
A blog post on Chris Blattman or Aid Watch is thus equivalent to an extra 7-9 months of abstract views, and 4-6 months of downloads.
The impacts of Freakonomics, Marginal Revolution and Paul Krugman are even larger – with the abstract view impact of 300-470 equivalent to 3 or more years of regular views, and the download impact of 33-100 downloads equivalent to 8 months to 2 years of regular downloads.
Exact and consistent data across all the blogs in our list are not available, but the data which are available suggest that the most-read blogs have significantly lower click-through rates than the more research-focused niche blogs. Marginal Revolution and Freakonomics are both estimated to have approximately 35,000-40,000 page views and 25,000 unique visits per day. This suggests a click-through rate of only 1-2 percent for abstract reads, and 0.1-0.4 percent for downloads.
Chris Blattman’s blog is estimated to have approximately 2,200 page views per day, suggesting a click-through rate of 4.3 percent for abstract reads and 1.1 percent for downloads. This seems consistent with the intuition that as an academic’s blog expands readership to a larger and larger audience, the additional readers are less likely to be interested in the academic papers.
They blog their findings here.
The niche blog finding sounds plausible. Though my hunch is that niche blogs like mine also have a higher proportion of feed readers than page views, which could mean my click through rate is lower than this estimate.
Then again, I have trouble figuring out my wireless mouse, let alone my blog statistics. So I will defer to Berk and David.