The Scottish Police Federation (SPF) said Mr Sarwar was “playing the race card” when he issued a press release on Monday suggesting those from ethnic minority communities are four times more likely to be stop-searched than their white counterparts.
The Independent Advisory Group on Stop and Search said the evidence did not substantiate that claim.
Led by John Scott QC, the group’s work was instrumental in leading to the outlawing of non-statutory (or “consensual”) stop and search, which had been used to target children.
As a result of the its work, a six-monthly review of statutory stop and search is being carried out by Susan McVie, a criminologist at Edinburgh University.
Mr Sarwar was accused by David Hamilton, the SPF’s vice chairman, of “wilfully presenting inconclusive data to insinuate racism” after he issued a press release saying police officers are “disproportionately targeting ethnic minorities”.
Professor McVie said the Labour press release had not taken account of a number of caveats in the report about drawing reliable conclusions based on population data.
She said: “I clearly stated in the report that the search rate for some non-white ethnic groups appeared to be higher than that for white people. However, we advised caution in comparing rates across different ethnic groups for a number of technical reasons. It is not credible to conclude that there is an inflated rate of search for specific minority ethnic groups based on these data.”
She added: “The claim that search rates for people from black and Asian backgrounds are four times higher than those for white people is wrong and demonstrates a lack of understanding in how to use and interpret this type of information. When looking at black and Asian people combined, the rate of search is 2.8 per 1,000 people – only a fraction higher than the rate for white people at 2.7 per 1,000.”
Responding to suggestions that positive searches were lower for those coming from minority backgrounds, Professor McVie said the differences could be explained by factors others than race.
She said accusations about institutional racism in Scottish policing were “unfair and unsubstantiated” if based solely on her data.
Mr Scott said: “Stop and search is an area of policing in Scotland which has been transformed in a short number of years in terms of transparency and scrutiny, both internal and external.
“Although the data does not support any claims of racial bias, we welcome any evidence of particular issues or concerns with the operation of the Code of Practice.”
Writing on Twitter, Calum Steele, general secretary of the SPF, said: “It is difficult to conclude anything other than this whole sorry saga was anything other than a premeditated insidious attack on the reputations of hard-working police officers purely for political advantage.”