# ISOBudgets blog by Rick Hogan

• ### 7 Steps to Calculate Measurement Uncertainty

Introduction Calculating measurement uncertainty is not easy. In fact, I speak with people every day who are having problems with estimating uncertainty. Therefore, I decided to put together this guide disclosing my exclusive seven step process to calculating measurement uncertainty. In this guide, you will learn how to calculate measurement uncertainty in seven easy steps. […]

• ### How to Estimate Uncertainty in Measurement for Chemistry Laboratories

Introduction Estimating uncertainty in measurement for chemistry laboratories is quite different compared to other types of laboratories. Most chemistry labs need to use two different processes to estimate uncertainty. Typically, there is one process to evaluate uncertainty for physical measurements and another process for analytical chemistry measurements. Although each uncertainty analysis uses the GUM […]

• ### How to Calculate Linear Thermal Expansion for Measurement Uncertainty

Introduction Thermal linear expansion is a source of uncertainty that you need to consider if you perform dimensional and mechanical tests or calibrations. Typically, it affects measurement results that involve length or displacement. However, it can also affect measurement results in the following categories: Pressure Torque Flow Volume Area When evaluating thermal expansion, most […]

• ### How to Calculate Hysteresis for Your Uncertainty Budget

Introduction Hysteresis is a source of uncertainty that affects many types of measurement equipment and their associated measurement results. With a quick search on the internet, you will find a lot studies dedicated to hysteresis. If you take a look at manufacturer manuals and datasheets, you may find specifications related to hysteresis. However, […]

• ### How to Calculate Linearity Uncertainty

Introduction Linearity uncertainty (a.k.a. linearity error or non-linearity) is a source of uncertainty that should be included in most uncertainty budgets. It is a common characteristic published in the manufacturerâ€™s specifications for various types of measurement equipment. However, I do not see it included in uncertainty budgets as often as it should be. If […]

• ### Proficiency Testing and Interlaboratory Comparisons: The Ultimate Guide to ISO/IEC 17025

Introduction Proficiency testing is an important element of ISO/IEC 17025 accreditation. So important, that it has its own ISO standard (i.e. ISO/IEC 17043). In addition to the international standard, proficiency testing has plenty of endorsement via ILAC and accreditation body policies. There is a ton of information on proficiency testing available to laboratories seeking […]

• ### How to Start Every Uncertainty Analysis

Introduction Each time that you begin an uncertainty analysis, you need to create an outline before you start to estimate uncertainty. I call this process specifying your measurement function. It is the first step in my 7 Steps to Estimating Measurement Uncertainty Guide. However, it is simply creating an outline for your uncertainty analysis. […]

• ### How to Report Uncertainty in Measurement

Introduction Reporting measurement uncertainty in test and calibration certificates is a common practice for ISO/IEC 17025 accredited laboratories. It is also a common problem for a lot of laboratories. Many struggle to do it right. Most accredited laboratories are required to include uncertainty in their certificates. However, many of them do not know how […]

• ### How to Find Significant Contributors to Measurement Uncertainty and Automate the Process in 5 Steps

Introduction Ever wondered what factors are significant contributors to uncertainty in measurement? Are you performing an uncertainty analysis and wondering what components to include in your uncertainty budget? Maybe an assessor cited you a deficiency and recommended that you include more sources of uncertainty in your budgets. Afterward, they provided you with a laundry […]

• ### Type A and Type B Uncertainty: Evaluating Uncertainty Components

Introduction Type A and Type B uncertainty are two elements that are commonly discussed in estimating measurement uncertainty. Uncertainty type is covered in most measurement uncertainty guides and uncertainty training courses. Auditors review uncertainty budgets to make sure the components are categorized correctly. However, have you ever looked at most of the information published […]