At first you'd think there was a serious problem, until you look at the number of respondents to this survey.
'The responses of 67 principals, 150 teachers and 75 support staff were analysed.'
What is the total number of principals, teachers and support staff cuurently employed in NZ? Somewhere between 20,000 and 30,000 possibly?
You'd have to wonder why so few people completed this 'survey.' You'd also wonder if only those who have experienced or seen an assault on a colleague responded. Perhaps all the others were too busy marking exams or thinking up ways to make NCEA worse or looking at child porn on the school computer.
This reminds me of the Bradford inspired 'statistical evidence' for the claima couple of years ago that one in ten NZ children were subjected to family violence.