Tiered calculation method

One possible way to approach the topic is the use of so-called tiered calculation methods. Based on the analysis of individual cost factors and their impact on the overall effort, a first, in many cases already sufficient, basis for financial evaluation of technical requirements and design parameters is created. With more experience, it is recommended, despite higher time expenditure in the beginning, to create a detailed calculation, company specific for the mold vendors and at least industry-specific to the mold maker for the buyer. In addition to an objective basis for the technical specification and the economic evaluation of a mold (e.g., in the form of a negotiation support), the detailed calculation is also a necessary standard and calibration instrument for all types of simplified cost calculation. 

Data-dependent uncertainty factors might be identified as a probabilistic variant of a simple generic approach. For example, calculation of the lower confidence limit of the 95% confidence interval of the 5th centile of an SSD can be considered a statistically derived UF. The UF, when presented, would be different between substances, depending on the available data. Next to the use of SSD-derived UFs, whereby SSDs are considered Tier-2 methods (because they are of a statistical kind), other methods could be envisaged to derive Tier-lb — data-driven uncertainty factors. 

In 2000, the U.S. EPA published requirements for tier 2 fuels and also mandated the test methods that can be used for sulfur determination in these fuels. ASTM D 6428 was chosen as the mandatory method for diesel fuels with ASTM D 2622, D 3120, and D 5453 methods allowed as alternates if their accuracy and precision were shown to be equivalent to those of D 6428 method. The petroleum industry widely uses the latter three test methods for sulfur but had virtually no experience with the mandated D 6428 method, which is under the jurisdiction of ASTM D 16 Committee on Aromatic Hydrocarbons and Related Chemicals. The method was written for the sulfur determination of liquid aromatic hydrocarbons, their derivatives, and related chemicals. The precision quoted in this method was for aromatic hydrocarbons and not for petroleum products. Moreover, it was inadequate (10 analyses by one operator on two samples) and did not conform to the statistical protocols used in the D02 Committee test methods for calculating the precision and bias estimates. 

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