Papua New Guineans have lost nearly half of the economic power they had in 1980, according to economist Paul Flanagan.
Mr Flanagan, from the Australian National University, has worked in PNG and studied the economy for many years.
He said the focus of successive governments on resource development had brought few gains for the people.
He said the average Papua New Guinean's economic wellbeing has fallen dramatically since 1980.
"Some people in areas of Port Moresby would have done very well since 1980, but on average, across the country as a whole, it means people in PNG are able to buy less goods and less services relative to 1980."
"They have gone back by 40 percent in real terms, " he said.
Mr Flanagan said politicians needed to focus on the country's real resource, which is its people.