There is no absolute accuracy in measuring, nor is it required. Varying degrees of precision are necessary depending on the job. One will measure more precisely sometimes and not at others depending on conditions, equipment and attitude. Every observation is subject to variation.
Now someone's challenging your measurement. Be it your boss, another employee, an inspector, or a customer. Measurement variation is present every time a part is measured so it's expected that challenges might occur. How do we resolve the problem?
The following are eight principles of conflict resolution that I developed for my repair business. They might not be adaptable to everyone's situation, but they should point the way toward reducing such conflicts and making better measurements. Read more in ebook.