Probability of False Accept - Free Excel Worksheet. Decision Rules can be difficult to understand, but this worksheet will help. Use this tool to input parameters such as accuracy requirement, resolution, measurement uncertainty, and repeatability with other error sources. It will help make decisions on equipment, such as: Should I buy a device with better resolution? Do I need my calibration provider to have better measurement uncertainty than what I am getting? It also provides different Methods, using different decision rules (Method 5 and 6). The PFA calculator contains macros.