Will differences between measurements obtained using old vs. new instructions be greater than the formal uncertainty of measurement?
No. Measurements made with old or new instructions will differ by less than the uncertainty established in the precision and bias section of D 4417, ASTM’s standard governing replica tape roughness determination. Testex has always called attention to the fact that “replica tape measurements are most accurate near the middle of each grade’s range”. The new instructions offer a formalized way to act on that guidance and will provide better accuracy and consistency. I am surprised that the uncertainty of measurement cited in the ASTM standard is as large as it is. ASTM has a very careful and rigorous testing and analysis procedure but the calculated uncertainties in the current version of its D4417 standard were derived from tests that mistakenly included surfaces outside the specified range of the tape. This is believed to have resulted in unrepresentatively large error bars. New testing in support of a revised Precision and Bias section for ASTM standard D4417 is scheduled for late 2010
Related Questions
- Even if modest compared with the formal uncertainty, there can be differences between measurements made using old and new instructions. How do I handle this at a job site?
- What are the differences in the results obtained performing ping and traceroute using Looking Glass vs. performing the commands directly from the router on my premise?
- How is access information (User ID, password, instructions) to HSCP obtained?
