FIG. 3.

Rat Grimace Scale analysis procedure. After video capture, an investigator naïve to the experimental groups captured screen shots from the digital recording. Another investigator naïve to the experimental groups placed each screen shot onto a PowerPoint slide, gave each slide a unique coding number, and randomized the slides using a randomization matrix. Two investigators naïve to the experimental groups scored each slide, and the scores were averaged. Derandomization was conducted by a separate investigator as was final data analysis. Thus, a minimum of four investigators were involved to maintain anonymity of experimental conditions (i.e., injury or control and before or after acetone).