Few debates about academic methodology result in a researcher being labelled a “posh socialist ‘activdemic’” or another being told that her work is akin to a BNP leaflet. But this is no ordinary academic debate. It’s about Asian “grooming gangs” and a report on the issue published last year by the anti-extremism thinktank the Quilliam Foundation.

Thanks to a series of high-profile court cases, the question of Asian and, specifically, Muslim grooming gangs has become an incendiary issue. Quilliam and its chairman, Maajid Nawaz, divide opinion. For some, they are a scourge on political correctness, bravely shining a light on dark corners of Muslim communities. For others, they give succour to bigots.

The Quilliam report, Group Based Child Sexual Exploitation: Dissecting Grooming Gangs, written by Haras Rafiq and Muna Adil, claims that 84% of grooming gang offenders are Asian, the majority “of Pakistani origin with Muslim heritage”. That figure quickly caught the headlines, cementing the narrative of an “epidemic” of Asian grooming gangs.

The report faced fierce criticism from academic researchers. Ella Cockbain, a lecturer in security and crime science, is an expert on child sexual exploitation. She said it “is a case study in bad science: riddled with errors, inconsistencies, a glaring lack of transparency, sweeping claims and gross generalisations unfounded its own ‘data’”.

The latest controversy began with a celebrity. Lily Allen tweeted that the report had been “outed as being utterly useless”. Cockbain backed her up, calling it “utter rubbish”. Nawaz denounced both as “Disgusting #RegressiveLeft neo-colonial hypocrites”. And so it went on.

Beyond the inflammatory rhetoric, what are the facts? Surprisingly few. Certainly, the media have highlighted many cases involving Asian men grooming girls, often white, for sexual exploitation. Media coverage is, however, a poor gauge of facts.

Nazir Afzal is the Crown Prosecution Service’s former lead on child sexual abuse and the prosecutor most responsible for bringing down grooming gangs. The media, he observes, pounce on cases involving Asians, but often ignore those involving white perpetrators.

“Grooming gang” is not a legal category. Group-based child sexual exploitation (CSE) falls under a range of offences, from rape to conspiracy to incite prostitution. In only some cases, often when non-whites are involved, is ethnicity recorded. All this makes it difficult to ascertain the facts and behoves us to be cautious.

Using “extensive data mining methods”, Quilliam researchers found 58 cases between 2005 and 2017, leading to 264 convictions for “group-based CSE involving grooming tactics”. There is no information as to where the data comes from, how it was selected or how ethnicity identified. Of the 264, 222 were Asian, hence the figure of 84% of grooming gang offenders being Asian. Just 18 were white.

Critics have pointed out, however, that even a casual media search produces far more white perpetrators of group CSE who seem to have been ignored by Adil and Rafiq. And 58 cases over a period of 12 years seems exceptionally low. As the Quilliam report itself notes, a Child Exploitation and Online Protection Centre (CEOP) study found 57 cases of Type 1 offending (in Quilliam’s eyes, the equivalent of grooming gangs) in 2012 alone. Rafiq told me he was unsure about the reasons for the disparity but that it may be a difference between grooming cases and court convictions.

In many small towns, Asians control the night-time economy – working in takeaways or driving minicabs

Given all this, the figure of 84% of grooming gangs being Asian seems dubious. There have, however, been previous studies suggesting disproportionate Asian involvement. Two CEOP reports, in 2011 and 2013, noted that the data was so “incomplete” and “inconsistent” that one could not “draw national conclusions about ethnicity”. Nevertheless, data available suggested “a disproportionate number of offenders… as Asian”.

In 2012, Cockbain called the CEOP figures “striking”. Today, she is more cautious. “It is enormously difficult to separate out group and lone offences from large-scale national datasets,” she argues. Without a proper definition of what “distinguishes ‘grooming gang’ activity from other forms of child sexual abuse, it simply isn’t possible to measure the scale or characteristics of offenders”. Quilliam researchers disagree, but have produced no methodology to assuage the concerns.

Equally contentious is the question of why Asians may offend. The Quilliam report blames the “culture” of Muslim communities. Those who deny this are being “politically correct”.

No one could accuse Afzal of political correctness. He has pushed through prosecutions of Asian offenders, often in the face of considerable resistance. The issue, he argues, is less about culture or religion than opportunity and circumstance. In many small towns, Asians control the night-time economy – working in takeaways or driving minicabs. Just as church schools or football clubs provided opportunities for certain types of men to commit sexual offences, so do such night economies.

The Quilliam report observes that “Asian CSE offenders represent 0.01% of the UK’s Asian population”. The attitudes of the perpetrators towards women undoubtedly shaped their actions. The social mores of many British Muslims are deeply conservative. Given the numbers involved, however, it is difficult to infer that the culture of particular communities is causally responsible for grooming gangs.

The cases of grooming gangs, the role of Asians, and of Muslims, and the failure of the authorities to take the issue seriously, raise important and complex questions. The manner in which the issue has been debated, however, has been abysmal.

There is an assumption of bad faith. Cockbain has implied that Quilliam’s argument is driven by a desire for funding. One of her detractors hinted darkly (and without providing any justification) that her motivation is “other than academic”.

There is guilt by association. The fact that the far right has made use of the Quilliam report is seen by some as tainting it. A Quilliam source suggested that Cockbain’s criticisms were damned by the fact that “jihadists gleefully egg her on”.

There is dismissal by label. “Vicious white #regressiveleft socialists will never accept PoC [people of colour] breaking away from their script. Their Orientalism stinks,” Nawaz tweeted. When it suits, Quilliam researchers are happy to exploit their racial identity to deflect criticism.

There is nothing racist about asking whether Asians or Muslims may be disproportionately represented in any form of crime. That doesn’t mean that any investigation or claim should be uncritically accepted. There is equally nothing racist about white researchers calling out the work of non-whites as shoddy.

These are terrible crimes. There needs to be a proper public debate. The victims, indeed all of us, deserve better than this.

• Kenan Malik is an Observer columnist