While results for only about half of the 13 scenarios tested are complete, four looked promising, Southern District Health Board chief operating officer (Otago) Vivian Blake said.
The modelling had shown that the number of people with the least urgent conditions turning up had increased.
Reducing the number of attendances which could be dealt with by GPs appeared to be the aspect which could make the biggest difference to the amount of time spent in the department.
A scenario testing the effect of a short stay unit for patients whose conditions might need monitoring for some hours before being sent home or admitted to a ward could reduce the number of patients staying beyond the target six hours by up to 10%.
Rostering on more senior registrars, particularly at weekends, and increasing the fast-tracking of patients from its existing limited Monday to Friday hours to 16 hours every day were two possible changes which could make a difference.
Mrs Blake said more work had to be done on the data, however, as some of it was 12 months old.
Work comparing the night staff cover at Dunedin with other hospitals was also needed.
She remained convinced a short stay unit or similar would be required if the board was to achieve the target of having 95% of patients spend no longer than six hours in the department.
A report was being prepared for the hospitals' advisory committee on such a unit.
The hospital has been languishing near the bottom of national tables on the emergency department waiting time target, with about 70% of patients being treated and discharged or transferred to a ward within the six-hour target.
The board is taking a whole-of-systems approach to the issue with a project called "6 Hours - It matters!"
This will include hearing from patients about their emergency department experiences at a meeting in Mosgiel on April 12.
