The consultancy at the centre of a storm over Facebook data greatly exaggerated its role in Donald Trump's 2016 US Presidential victory and would not have been able to sway an election result, the academic who provided the data said.
Psychologist Aleksandr Kogan also told the BBC that he was being made a scapegoat by Facebook and Cambridge Analytica, a British-based company hired by Mr Trump for his election campaign.
Facebook has been rocked this week by a whistleblower who said that Cambridge Analytica had improperly accessed information on millions of Facebook users to build detailed profiles on American voters.
The revelation has knocked nearly US$50 billion off Facebook's stock market value in two days.
Facebook and Cambridge Analytica have both blamed Mr Kogan, an academic at Cambridge University who gathered the data by running a survey app on Facebook.
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However, Mr Kogan said the services provided by the UK political consultancy had been greatly exaggerated.
"I think what Cambridge Analytica has tried to sell is magic, and they've made claims that this is incredibly accurate and it tells you everything there is to tell about you. But I think the reality is it's not that," he said.
Mr Kogan's smartphone application, thisisyourdigitallife, offered a personality prediction and billed itself on Facebook as "a research app used by psychologists".
Facebook says Mr Kogan then violated its policies by passing the data to Cambridge Analytica for commercial use, saying on Friday he "lied to us".
Cambridge Analytica said it destroyed the data once it realised the information did not adhere to data protection rules.
Mr Kogan said the events of the last week had been a "total shellshock".
"My view is that I'm being basically used as a scapegoat by both Facebook and Cambridge Analytica," he said.
"We thought we were doing something that was really normal and we were assured by Cambridge Analytica that everything was perfectly legal and within the limits of the terms of service."
British Prime Minister Theresa May told Parliament she backed an investigation into Cambridge Analytica, while a German government spokesman said that using data from 50 million Facebook users for political purposes would be unacceptable.
Alexander Nix, the head of Cambridge Analytica, said in a secretly recorded video broadcast on Tuesday that his company had played a decisive role in Mr Trump's election victory.
"We did all the research. We did all the data. We did all the analytics. We did all the targeting. We ran all the digital campaign and our data informed their strategy," Mr Nix told an undercover reporter working for Britain's Channel 4 News.
Mr Nix was suspended by the company shortly before the video was broadcast.
Asked by the BBC if he was willing to cooperate with lawmakers investigating the case, Mr Kogan said "absolutely".
"I think there's a really big question here in terms of how do social media platforms actually use everybody's data," he said.