This particular paper can be downloaded and read here. The results of the investigation reveal that although the increase in FCI scores was not statistically significant (an increase in the averaged normalized gain from 0.465 to 0.475), there was a significant increase in scores on the multiple choice section of the AP-C. Notably, the teacher identified a dramatic improvement in student affect toward class discussions of multiple choice problems. "Students seemed more engaged and invested in discussing their ideas about physics when the subject of that discussion [involved the use of clickers]."
Though PER is thriving in universities across the country, there continues to be very little direct research into the efficacy of Physics First. Developing a controlled study of the effect of a given method in a high school is challenging, given small sample sizes and wide variations in factors affecting student performance. Perhaps a research prize targeted specifically for ninth grade physics teachers could encourage teachers to investigate the impact that their own classes have on local populations.