I have several discrete datasets with a small range (-2 to +2) which I want to test against the null hypothesis "the distribution is centred around zero".
The Wilcoxon signed-rank test was suggested to me as an appropriate choice, and some answers on this site back this up. The issue is that, for some datasets, a large portion of the pair deltas are 0, meaning most of the samples are discarded. The result is that some datasets pass the test at 95% confidence while others with nearly identical distributions fail it.
What would be a good alternative test for such a scenario?