One of Coca-Cola's fastest-growing products, Frozen Coke and Frozen Fanta, was not included in the latest industry-funded study on soft drink consumption in Australia, which says we are drinking less of the sweet stuff than we were 15 years ago.

Coca-Cola Amatil, which markets the drinks under the brand names Fancy Coke and Fancy Ice Whirl, was excluded from the analysis because it was a cordial concentrate.

Other sugary drinks excluded from the study's scope included fruit juices, alcopops and flavoured milks which have significant market penetration in Australia.

Last year Coca-Cola Amatil told investors the company had created a "new beverage occasion" with Frozen Coke and Fanta Icy Whirl. Sales had grown by 44 per cent and 6,000 frozen beverage machines had been rolled out across Australia.

The new industry study comes as questions are raised over whether Australians are drinking more soft drink than in previous decades and about the link between sugar-sweetened soft drink and Australia's escalating obesity problem.

Last week, Radio National's Background Briefing program investigated flaws in another scientific paper, The Australian Paradox, which claimed consumption of sugar-sweetened drinks had fallen by 10 per cent.

Background Briefing reported that consumption had actually gone up by 30 per cent. The academics issued a correction to these "inadvertent errors".

The Quenching Australia's Thirst analysis was published two weeks ago by the Journal Nutrition and Dietetics. It found consumption of sugary drinks had fallen from 84 litres per person on 2006 to 72 litres per person in 2011.

The analysis was funded by the Australian Beverage Council, the industry lobby group representing sugary drink and fruit juice manufacturers in Australia.

Bill Shrapnel and Dr Gina Levy were each paid a consultancy to conduct the analysis and write the paper.

However excluded from the analysis were fruit juices, flavoured milks and cordial concentrates, either because the data was unavailable or because it fell outside the definition of "ready to drink".

Mr Shrapnel says the study relied on a consumption behaviour study conducted by AC Nielsen and commissioned by the Australian Beverage Council.

The study of 10,000 families asked participants to scan all household purchases from supermarkets, convenience stories and pharmacies for a year.

Based on these results, and individual interviews about these purchases, the study calculated another set of numbers to then impute consumption of soft drinks in bars, hotels and from vending machines.

These findings were then extrapolated into the AC Nielsen data to arrive at a total consumption number.

These extrapolations and imputations are not publicly available because they are confidential industry data.

"Dr Gina Levy got the data from industry and I wrote it up," Mr Shrapnel said.

Asked if he had examined the assumptions behind the imputations, Mr Shrapnel said he had not.

"You'd have to ask Dr Levy about that, but unfortunately you can't. She is now employed by Kellogg's and she won't speak to you" Mr Shrapnel said.

Dr Levy was employed by Kellogg's last month as their national communications manager.

The Quenching Australia's Thirst analysis also excludes ready-to-drink alcoholic beverages or alcopops and fruit juice, frozen slushies and sweet milk drinks.

According to Australian Beverages Council data, Australians drank on average 23 litres of orange juice, while the Dairy Council reports we each drank 12 litres of sweet milk products last year.

Mr Shrapnel said the orange juice data was excluded because in 2007 juice companies were not members of the Australian Beverage Council.

"We didn't have that orange juice data," he said.

According to Mr Shrapnel, the limitations of his data did not change his view that sugary drink consumption was falling in Australia.