Table A3.

Descriptive statistics: Methods for NSSI

Method for NSSI	n	%	κ	agreement
Cutting	461	92.2	0.21	fair
Hitting; bruising	86	17.2	0.81	almost perfect
Scratching; picking	72	14.4	0.67	substantial
Burning	68	13.6	0.86	almost perfect
Biting	24	4.8	0.87	almost perfect
Starving; food restriction	21	4.2
Purging	7	1.4
Overdose	7	1.4

Methods for self-injury in descending order of the number of r/selfharm users (n = 500) mentioning having used that method at least once. κ = Fleiss’s kappa statistic, an indicator of intercoder reliability. Interpretation of κ (from Landis & Koch, 1977) is also reported. All values of κ were significantly better than chance agreement at the P < 0.001 level. Items with associated κ’s are from an a priori codebook, while no κ’s are reported for additional methods added to the codebook post hoc. These additional items were mentioned by at least 1% of users (n = 5), after resolving disagreements between coders.