User blog comment:Eles99/Study of Shelling Critical Hit/@comment-24430017-20140508190703

Sample size required will depend a lot on how different the results are. I think it would be more effective to try with a CL like Yuubari. They can equip type 32 for the +8. 3-4 of those would be +26-32 accuracy.

Higher level ships should also have higher accuracy, so you might compare high level ships vs low level ones. Although you won't be certain its accuracy with this method. I do seem to get the impression that my high level DD crit a lot more.