How are wait times calculated in Ocean?


Ocean uses appointment dates and other information stored in its referral database to automatically calculate and display up-to-date wait times within the Ocean Healthmap.

These estimated wait times serve as a useful consideration for referrers when deciding which health service provider is most appropriate for a patient.

For example, the wait times may assist primary care practitioners (PCPs) in finding an orthopaedic surgeon for a patient with a much shorter wait time for knee surgery when compared to the PCPs usual "go to" list of surgeons.

Currently there is no up-to-date, published information on wait times for most health services in Canada, making Ocean's reported wait times a very useful resource for referrers.


Wait 1 is an industry-standard term that represents the time from the sending of the referral to the date of the first consultation with the health service provider.

  • Wait 1 may be divided into two smaller wait times, Wait 1a and Wait 1b, which are used when an initial assessment centre is involved prior to seeing the specialist (such as a knee joint assessment clinic).
    • Wait 1a is the time that elapses within Wait 1 between the sending of the referral and the initial screening assessment.
    • Wait 1b is the time that elapses within Wait 1 between the decision to proceed with a specialist consultation and the date of the consultation.

Wait 2 starts after the first consultation, when the decision occurs to proceed with a surgery or other intervention (a decision which happens usually, but not always, on the date of the consultation).

The wait times are sometimes manually adjusted to exclude certain date ranges that would negatively impact a wait time. For example, if a patient heads south for the winter and is unavailable for treatment, the wait time may be adjusted to exclude this time period. These date ranges are called Dates Affecting Readiness to Consult (DARC) and Dates Affecting Readiness to Treat (DART).

How the Calculation Works

The wait times are calculated entirely from the sample of referrals that are stored within Ocean. Some referrals included are true eReferrals, and others are faxed referrals that have been transcribed into Ocean and had their appointment dates manually entered.

Each night, Ocean looks at the collection of eligible referrals sent to every individual health service offering in the system.

Ocean uses these referrals to calculate an average Wait 1 and Wait 2 time for this service offering.

For example, an MRI offered at a particular hospital listing will have its own independent Wait 1 and Wait 2 time calculated, independent from the wait times for a CT offered at the same listing.

In addition, Ocean calculates a standard deviation for Wait 1 and Wait 2, to give stakeholders a sense of the variation in wait times for the service offering.

Referrals that are included in the sample (unless specifically excluded):

For a given health service offering at a listing, referrals are included in the calculation by default when the referrals:

* A special case exists for Rapid Assessment Clinics: Referrals seen at a rapid assessment clinic are included in the rapid assessment clinic's Wait 1a and Wait 1b calculation, even when they have been forwarded on to the specialist listing.

Referrals that are excluded:

  • Referrals sent more than 180 days ago (6 months)
  • Declined referrals
  • Test referrals
  • Referrals that are tagged with a reason-for-wait-time-exclusion by the provider or central intake, e.g.:
    • An earlier appointment was offered but declined by the patient
    • The patient requested or rescheduled to a later date
    • There was repeated difficulty contacting the patient
    • The patient was a pre-existing client
    • The original referral was redirected

Caveats of Wait Time Calculations:

  • The wait time calculations above represent an average based on a (sometimes small) sample of referrals within the system. Consequently, the wait times' accuracy will vary significantly from service to service.
  • The calculated wait time does not guarantee in any way that a patient will be seen within a specific timeframe.
  • Individual wait times may vary depending on the nature of the specific service provided. For example, within a general MRI service offering, an MRI of the foot may have a longer wait time than an MRI of the brain.
  • The wait times may also vary based on the site's triaging. For example, referrals deemed to be urgent will frequently have shorter wait times than routine referrals.

Sample Size Considerations

For each independent wait time calculation, a minimum sample size of 6 referrals is required prior to the presentation of any wait time value. Health service offerings with values less than this value will show "Unavailable" as the calculated wait time.

Sample sizes less than or equal to 10 are flagged with an asterisk to alert users to the potential inaccuracy of the calculation due to sampling errors.

Why are referrals sent more than 180 days ago excluded?

Ocean uses a 180-day running average Wait 1 time, as it is most predictive of what the referral sender's wait time will be. This 180-day snapshot is long enough to provide an adequate sample size, but not so long that it would suffer from stale sample data. Ocean calculates and stores the wait time for all eligible referrals in its analytics, but it also does a separate calculation specifically for the Ocean Healthmap using eligible referrals sent within the past 180 days. It displays the wait time only for this relatively recent subset.

For example, if a clinic has hundreds of referrals received ~2 years ago each with a wait time of 6 months, but the clinic has since become backlogged and every referral received in the past 6 months each has a wait time of 3 years, an 'average of all-time' wait time calculation would result in a misleading ~1 year wait time, rather than the reasonably accurate 3 year wait time.

Conversely, if a clinic previously had a true 3 year wait time for many years, but has recently cleared their backlog and now offers next-day appointment, an 'average of all-time' wait time calculation would provide a long and misleading wait time. It would take many years before this calculation reflects the truly accurate next-day wait time.

Implications For Providers:

Most of the work to calculate wait times is handled automatically by Ocean as part of the routine use of the system. For example, whenever an appointment is entered for a referral (which providers are incentivized to do for other reasons, such as provider and patient appointment notifications), the referral is included in the wait time calculation.

Wait Time Management

Health service providers in Ocean should take the time to appropriately tag ineligible referrals for the exclusion reasons listed above. Otherwise, Ocean will include them in the calculation.

Providers should also enter DARCs and DARTs for referrals (when applicable) to ensure the recorded wait times reflect each referral's true waiting period; otherwise, the wait times will appear worse than they are in reality.

Providers should exclude outliers when appropriate. For example, referrals whose wait times are not determined by queuing, such as timed follow-ups, are usually excluded from the calculation.

For more information please see these articles:

Disputes and Clarifications Regarding Wait Times

If a provider is concerned about referrers or patients receiving misleading information from these calculated wait times, we recommend the following:

  • Review the referrals at the provider's site to ensure outliers are excluded when appropriate.
  • Enter DARCs and DARTs to ensure referrals with artificially prolonged wait times are adjusted appropriately.
  • Set the Health Service Offering's Self-Reported wait time to match the provider's understanding of the correct wait time. This Self-Reported wait time can help inform referrers when the calculated sample may differ from real-world referrals. For more information on managing your calculated and self-reported wait times, please refer to Managing Calculated and Self-Reported Wait Times.
  • Include a Public Comment in the wait time management area for the Health Service Offering. This comment can provide important context, particularly when the service's Self-Reported wait time differs significantly from the calculation, or when specific protocols may influence the referral's wait time.


Please Note:

Ocean wait time calculations may differ from other system calculations such as Wait Time Information System (WTIS).

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