In our analysis, we only included Github repositories that had more than 1 star since that would be a better indicator of the quality & commitment of the developer community. Since, both platforms are open source, the strength of the developer community drives overall adoption.
The analysis from the above chart shows that Raspberry Pi started picking up in Q2 of 2012 with 83 additions. In Q3 of 2012, one can clearly see the growth of Raspberry Pi (129 additions) with Arduino declining in the same period to 226 (Q2 2012 additions were 330). In Q4 of 2012, the additions become neck & neck with Raspberry Pi at 146 & Arduino at 195. The additions after that stay fairly closely to each other after Q4 2012.
The developer trends in Github is also reflected in Google Search trend data from Jan 2012 to April 2014. This should correlate in open source projects since developers could drive consumer & overall interest in the projects.
We also examined a snapshot in time look at four different metrics.
Google search trends over the past 30 days (May - June 2014) show Arduino ahead but the nuances are in the above chart
Arduino has almost 3 times 1 star Github repositories compared to Raspberry Pi. This is because of the longer history of Arduino & when we look at net Github additions (above) they are fairly close
On social media, Raspberry Pi is doing a very good job by having about 2 times more followers than Arduino even though they started later.
On Facebook, Arduino is way ahead with 4 times more likes than Raspberry Pi