Quantitative research heavily depends on the accurate measurement of variables using scales. The choice of these scales significantly influences the validity and reliability of research outcomes. This paper aims to determine the most reliable and valid scale for further research, using the selection of a personality traits scale as a case study. A comprehensive review of existing personality traits scales was conducted, followed by a quantitative study involving 696 college students from a college in Shandong, China, using convenience sampling. The study evaluated three scales: the Simplified Chinese Big Five Personality Inventory (SCBFPI-40), the Brief Big Five Inventory (BFT-10), and the Big Five Inventory (BFI-44). The BFT-10 demonstrated low reliability, with Cronbach's α below .500. The BFI-44 showed moderate to good reliability, with α values between .682 and .811. The SCBFPI demonstrated high reliability, with α values over .800 for all dimensions, indicating it is a robust tool for assessing personality traits among Chinese students. Scale selection significantly impacts research reliability and validity. The SCBFPI's high reliability suggests that culturally adapted scales provide more accurate measurements, whereas the BFT-10 may not be suitable for Chinese populations. Proper scale selection enhances data accuracy and research robustness. Researchers should prioritize culturally validated scales like the SCBFPI for reliable results.