Cause of death: where there is no physician
Tariff is a simple method that assigns a score or ‘tariff’ to an item in the questionnaire according to the number of times a respondent answered ‘yes’ to a symptom question for a particular COD.
In other words, the Tariff method identifies the strength of association between a symptom and a specific COD, based on the ‘signal to noise’ ratio (eg how closely was a particular symptom linked to a specific cause (‘signal’) compared to how frequently it was associated with other, un-related causes (‘noise’). That is, certain symptoms (such as ‘cough’) will be statistically associated with certain diseases (such as major respiratory diseases) more than with other conditions (such as heart attacks). Tariff scores are calculated for an individual death by applying the pattern of responses from the VA interview to a known matrix of Tariff scores, where the true cause of death is known (using the PHMRC Gold Standard VA dataset) and a COD is then assigned to each individual death by ranking the tariff scores based on reported symptoms.
The method is entirely data-driven and does not rely on external expert opinion about symptom-cause associations. Free software (SmartVA-Analyze) to collect and analyse VA responses, as well as essential training materials including the interviewer’s manual and user guides. Read more about more about SmartVA.
Institute for Health Metrics and Evaluation. Verbal autopsy tools.
Serina P et al (2015). Improving performance of the Tariff Method for assigning causes of death to verbal autopsies. BMC Medicine.