One in 15 people covered by the General Medical Scheme is currently on a waiting list, compared with one in 50 of those with private health insurance, according to the ESRI report.
Patients with a medical card wait for 16 weeks for a hospital bed, on average, compared to 14 weeks for those with no cover. Those with private health insurance wait an average of eight weeks.
Two-thirds of people without private health insurance are not covered because they cannot afford it. Even if waiting lists get longer, most of the non-insured could still not afford private insurance, the ESRI found.
Ninety-six per cent of people believe the Government should bring public waiting lists into line with waiting times for private patients.
Ninety-five per cent believe the Government should spend more on public health to reduce waiting lists.
One person in four has no medical insurance cover of any kind. They are concentrated in the under-20 age group and are slightly more likely than those with private health insurance to have a health problem.
Just under one-third of adults are GMS members, 45 per cent of adults are covered by private health insurance or a workplace health plan, 6 per cent have a hospital cash plan.
Eighty-five per cent of those with private health insurance belong to the VHI, eight per cent are covered by BUPA-Ireland and 7 per cent are covered by work-based schemes.
Concern about the length of wait for treatment in the public health system was cited twice as often as fears about the quality of public hospital care when making the decision to opt for private health insurance, according to the ESRI.
The overwhelming majority of people across all social, income, age and educational categories - whether privately insured or not - wants more money spent on health services.
Over half (52 per cent) think that money should be raised through the introduction of compulsory private health insurance for those over a certain income.
A quarter believe the Government should raise taxes, one-fifth think the Government should reduce spending on infrastructure, and more than one-third would favour funding through "some other mechanism".
These include using the present Government surplus or National Lottery funds, improved efficiency in use of Government funds, and reducing TDs' salaries and expenses.
Nearly two-thirds of people (62 per cent) believe that private health insurance should be compulsory for those on higher incomes.
When this figure is broken down by socioeconomic group, it appears that those with less education and on lower incomes are most likely to favour compulsory private health insurance (67 per cent) compared with those in full-time employment (60 per cent) and third-level education (53 per cent).
People buy private health insurance because they do not want to wait for treatment, not because they think private treatment is better, the ESRI found.
"The insured and the non-insured were very similar in terms of their priorities and concerns: avoiding large medical bills and ensuring timely treatment were the most important reasons for having health insurance," it states.
Among the non-insured, two-thirds said it was unaffordable. Over half of the uninsured in the highest income category regard insurance as "too expensive". Over half of the non-insured would not be willing or able to pay for private health insurance.
Nearly two out of five of the non-insured in the highest income category are unwilling to pay for health insurance, and only about one-fifth are willing and able to pay more than £10 per week.
The basic message from the ESRI survey is that most people think they need private health insurance. Those who can afford it pay for it. Those who cannot are resigned to staying on the waiting lists.