The WET payable gap estimates are sensitive to the average wholesale mark-up rate used and the split of wine sold by domestic producers to either wholesalers, retailers or direct to the consumer.
We have not produced a confidence interval for the estimate of the WET payable gap. Each of the assumptions used in the top-down model has its own errors, many of which are unquantifiable.
We have not estimated non-compliance for the WET producer rebate as there is no suitable externally-provided aggregated data to estimate the value of incorrect or fraudulent WET producer rebate claims. We are in the process of using audit data in statistical bottom-up approaches to estimate the value of incorrect or fraudulent producer rebate claims.