ISO/IEC指南98-3/Suppl.1:20 08提供了一种通用数值方法，与测量不确定度表示指南（GUM）的广泛原则一致，用于执行测量不确定度评估所需的计算。该方法适用于具有单个输出量的任意模型，其中输入量由任何指定的概率密度函数(PDF)表征。 ISO/IEC指南98-3/Suppl.1:20 08主要涉及定义明确的物理量（被测物）测量中不确定度的表达，该物理量可以由本质上唯一的值来表征。它在不满足GUM不确定性框架的条件或不清楚是否满足的情况下提供了指导。例如，由于模型的复杂性，当难以应用GUM不确定性框架时，可以使用它。指南以适合于计算机实现的形式给出。 ISO/IEC指南98-3/Suppl.1:20 08可用于提供输出量的PDF(的表示)，从该PDF可以获得(a)输出量的估计，(b)与该估计相关联的标准不确定度，以及(c)对应于指定覆盖概率的该量的覆盖区间。 对于规定的覆盖概率，它可以用于提供任何所需的覆盖间隔，包括概率对称覆盖间隔和最短覆盖间隔。 ISO/IEC指南98-3/Suppl.1:20 08适用于独立的输入数量，其中每个此类数量都分配了适当的PDF，或者不独立，即。e.当这些量中的一些或全部被分配了一个联合PDF时。 详细的示例说明了所提供的指导。

ISO/IEC Guide 98-3/Suppl.1:2008 provides a general numerical approach, consistent with the broad principles of the Guide to the expression of uncertainty in measurement (GUM), for carrying out the calculations required as part of an evaluation of measurement uncertainty. The approach applies to arbitrary models having a single output quantity where the input quantities are characterized by any specified probability density functions (PDFs). ISO/IEC Guide 98-3/Suppl.1:2008 is primarily concerned with the expression of uncertainty in the measurement of a well-defined physical quantity—the measurand—that can be characterized by an essentially unique value. It provides guidance in situations where the conditions for the GUM uncertainty frameworkare not fulfilled, or it is unclear whether they are fulfilled. It can be used when it is difficult to apply the GUM uncertainty framework, because of the complexity of the model, for example. Guidance is given in a form suitable for computer implementation. ISO/IEC Guide 98-3/Suppl.1:2008 can be used to provide (a representation of) the PDF for the output quantity from which (a) an estimate of the output quantity, (b) the standard uncertainty associated with this estimate, and (c) a coverage interval for that quantity, corresponding to a specified coverage probability, can be obtained. For a prescribed coverage probability, it can be used to provide any required coverage interval, including the probabilistically symmetric coverage interval and the shortest coverage interval. ISO/IEC Guide 98-3/Suppl.1:2008 applies to input quantities that are independent, where each such quantity is assigned an appropriate PDF, or not independent, i.e. when some or all of these quantities are assigned a joint PDF. Detailed examples illustrate the guidance provided.