MPI managing director Steve Heather said the company conducted two polls on the subject - one in May before the recent federal election and one in November 2017 and compared the results.
It found there was a much higher no vote against Adani in 2019 after concerted campaigns by activist groups. The no vote against Adani increased from 46.45% in 2017 to 78.40% in 2019.
"We are in the unique position of being able to see ‘behind' the raw votes and assess things such as voting sources and voter demographics," Heather said.
"What became really interesting is how our recent poll on this subject was used by activists and how the poll results were skewed.
"After reviewing our summary, it should remind us all to remain ever sceptical about what we read, particularly with highly emotive subjects like coalmining, the environment and politics."
Heather said MPI knew the poll was skewed because it saw it shared on social media platforms with comments such as: "Come on, vote on this one and let's see if we can get the ‘No' vote right up there".
That would lead to a rush of votes.
There was an increase in people either not living in Queensland or not involved in the mining industry adding to the "no" vote.
When asked whether voters had heard any reporting about the mine, the number of people who voted "yes" jumped from 72% in 2017, to 91% in 2019.
"This is probably not a surprise as I'd imagine the words ‘Adani' and ‘coal' would be the two most quoted mining words throughout Australia over the past two years of intense energy-related debate," Heather said.
"The number of respondents to our poll jumped from just under 500 in November 2017 to in excess of 1000 in May 2019.
"Clearly this is a big, visible, polarising issue for a lot of people. No doubt the actual votes cast would have been very much affected by which of the four corners, or the middle, of this huge country voters came from."