The study comes from Jarno Zafelli and the engineering company Dromo. Zafelli has worked as a circuit designer for motorsports circuits and fast sports improvement since 2000. 
There are two versions of the study available, the public and the full version which features confidential data about each manufacturer. 

Dainese was the most racers' present manufacturer in 2013 with a total of 22 riders across all three classes of the motoGP World Championship (motoGP, Moto2 and Moto3). Alpinestars is second and Spidi is third. The Alpinestars riders gathered a total of 2056 points in the 2013 championship, the Dainese riders 1711 and the Spidi racers 1411. Although this is not a very interesting data, at the full version the study answers questions like “which has been the manufacturer who has best protected their riders, what is the medicalization ratio based on leathers manufacturer and class, what is the brand with the highest confidence from their riders, etc.”