I would recommend a lot more trials, with multiple test subjects and on multiple different days if possible. It could be the specs of the balls, or she's more comfortable throwing/hitting the 12".Interesting tidbit. My DD conducted an experiment for her science project: which ball would go further, 11" or 12". She did 3 trials of each size, throwing from home plate to the outfield, then hitting off a tee to the outfield. The 12" actually went further on both throwing and hitting, in every trial. Now this isn't an exact science but it was just her throwing and hitting so she was the constant (using same effort each time), we were surprised by the results. Science project is due next month and she is going to have to come up with a conclusion as to why LOL