Major gaps in the data estimating that up to a quarter of a million young people in New Zealand have been abused in state and faith-based institutions means we still don't know the full extent of the harm, especially among Māori.
Auckland University data specialist Andrew Sporle said the state's failure to record data properly - including the ethnicity of those in its care - meant it was almost impossible to know the scale and impact of the abuse.
The Royal Commission into Abuse in Care's interim report estimates that of the 655,000 young people in care between 1950 and 2019, nearly 40 percent were abused.
Sporle said it was startling to think of the data the report may have missed.
"The state didn't even care enough to keep proper records about who they were uplifting, what their circumstances were, what their ethnicity was and what happened to them. And then when they did keep records, they've acknowledged that a lot of those records got destroyed," he said.
"It makes it actually impossible to do two things. It makes it impossible to estimate the scale of the problem, and we know it was big, but it also makes it impossible to estimate the impact of abuse on our people."
Sporle said if one of his third-year students had submitted the report as an assignment, he would have failed them.
He said the publication's release was simply irresponsible, and he was concerned no in-depth analysis would be undertaken by the royal commission.
"What they should have turned around and said is, 'actually, the data is crap', that's being brutally honest," he said.
"What is convenient isn't necessarily right, and in this instance, we know it's not right, they know it's not right, but they've still decided to publish it anyway. In doing that, it takes the pressure off them to do more and to actually do the really in-depth stuff."
The report itself admits there are holes in the data, including that little is known about the ethnicity of those abused in care.
Oranga Tamariki's own figures give us an idea - with a recent report by the agency showing 81 percent of children abused in care are Māori.
Māori have been overrepresented in the care system since at least the 1960s, and continue to be today.
Abuse survivor Paora Crawford Moyle said in the state care facilities she grew up in, almost every child she knew was being abused.
"When I was a kid in state care it became the norm, and I saw lots come and go and you'd talk to one another and share stories of what happened to you and how you came to be under the care of the state.
"It was the norm that children were abused, and it was weird when they weren't."
She said the true number of children abused in care could be much worse.
"I'm thinking it's more," she said.
"I'm wondering how they're coming up with these numbers, who is doing the report writing, who is doing the investigating and what are they basing their figures on?"
The royal commission acknowledged there was also very limited historical data available on the number and proportion of disabled people in care.
Inquiry chair Coral Shaw said the interim report was an important part of its work to date but was by no means the end of what it would find out.
"We will continue to uncover much more about the nature and extent of abuse in care over the course of this inquiry which will inform our final recommendations to the Governor-General.
"We are indebted to the survivors of abuse in care who have come forward to share their experiences - some of whom have now passed on. Without them, there would not be an Interim Report," Shaw said.
The report is also based primarily on international studies, which focus more on physical and sexual abuse, rather than emotional and psychological abuse and neglect.
It said while there were gaps in the data, it was clear that more people had passed through the care settings examined than was previously known.