n (number of observations) x p (percentile value divided by 100) = i (integer) + f (fractional part of n x p)

• If n x p is an integer, then the percentile value will correspond to the average of the values for the i^th and (i+1)^th observations.
• If n x p is not an integer, then the percentile value will correspond to the value for the (i+1)^th observation.
• For example, if there were 100 hospital separations, the median will correspond to the average time for the 50^th and 51^st observations. If there were 101 observations, the median will correspond to the time for the 51^st observation.

Median waiting times are rounded to the nearest 0.5 whole number of days.

Waiting times are calculated for patients whose reason for removal was:

• For surgical specialty and indicator procedures:

1. Admitted as an elective patient for awaited procedure by or on behalf of this hospital or the state/territory.

• For clinical urgency categories:

1. Admitted as an elective patient for awaited procedure by or on behalf of this hospital or the state/territory or

2. Admitted as emergency patient for awaited procedure by or on behalf of this hospital or the state/territory.

The calculation of waiting time excludes:

• Any days the patient was waiting with a less urgent elective surgery urgency category than their urgency category at removal. When a patient's urgency category changes, existing NMDS business rules will apply.
• People who were transferred to another hospital’s elective surgery waiting list, were treated elsewhere but not on behalf of the hospital, were not contactable, died prior to receiving their surgery or declined surgery.

For the purposes of reporting by urgency category, patients are reported as the final urgency category they were when treated.

Waiting time is calculated by states and territories by subtracting the listing date for care from the removal date, minus any days the patient was not ready for care and/or waiting with a less urgent clinical urgency category than their clinical urgency category at removal.

There are inconsistencies in application of urgency categories between and within states and territories which impact on the comparability of results.