The formula given in the instruction manual was determined based on the experimental data detection. The laboratory conducted a series of negative control tests, including the use of different media (such as DMEM, 1640) and washing solutions (such as PBS), as well as tests on more than 20 healthy human serum samples *. These tests are designed to evaluate the materials used in the experiment (culture medium and washing solution) as well as the background noise or background value of human samples. Based on the results of the negative control test, the laboratory decided to add 0.02 (5 times SD*) to the average negative value as the Cut  The criteria for determining the off value. Such a setting is designed to ensure that the threshold for negative determination can cover all observed negative background values, while providing a certain margin of safety to ensure the reliability of the results. 5 times SD* : Under normal circumstances, 2 times the standard deviation (SD) is sufficient. The critical value increment of 0.02 was determined by the laboratory based on a large amount of sample data and is relatively universal within the recommended operating range of this kit. However, if the customer has higher-level requirements for the data, re-validation can be conducted during use to confirm the applicability of the critical values in specific experimental Settings.