Objectives: The aim of the study was to evaluate the analytical performance of the tests by calculating sigma values of some tests and to ensure that corrective actions were taken for the tests by presenting the differences between the sigma values calculated following different allowable total error (%TEa) standards.

Material and Methods: The present study has been carried out by using the data of internal quality control (IQC) and external quality control (EQC) studied between the dates 01/01/2020 and 03/31/2020. The evaluated tests were in 4 panels [Biochemistry (10 tests), Hormone-tumor markers (6 tests), Hemogram (5 tests), Coagulation (2 tests)].

Results: Significant differences were observed between the sigma values calculated according to the %TEa standards determined by different regulatory organizations.

When the sigma values calculated following CLIA 2019 %TEa standard of the two-level IQC data in a total of 23 tests, present in 4 test panels, have been evaluated by considering Westgard's sigma rules; it has been observed that 8 IQC results should be evaluated by 1_3s, 8 IQC results by 1_3s/2_2s/R_4s/4_1s multiple rules and 30 IQC results by 1_3s/2_2s/R_4s/4_1s/8_x multiple rules.

Conclusion: In the quality management and evaluation of the tests performed in the laboratory, while determining the tests that require improvement studies and determining by which rules the improvement studies will be carried out, the ratio of %TEa of the regulatory organization selected to calculate the sigma values gains importance.