<![CDATA[Deductive reasoning is at the core of rationality and is one of the main components that describe the level of intelligence. However, instruments for measuring deductive reasoning in Indonesia have limited accessibility, with unpublished psychometric properties. This study aims to develop an instrument for measuring deductive reasoning ability, namely the General Sequential Reasoning-Verbal (GSR-V), and examine its psychometric properties (reliability, validity, factor structure). A cross-sectional study was conducted with 163 students in grades 10, 11, and 12 from several senior high schools in Indonesia using convenience sampling. The instrument consists of two types of tasks: syllogism and conditional reasoning. Data were collected online and analyzed based on item difficulty, item discrimination, reliability, confirmatory factor analysis (CFA), and convergent validity. The results revealed that the 20-item GSR-V is reliable and exhibits a two-factor structure (syllogism and conditional reasoning) with adequate model fit. Additionally, convergent validity analysis indicated that the GSR-V meets composite reliability and factor loading standards, although the average variance extracted (AVE) values were insufficient. The GSR-V has proven to be quite reliable and valid in measuring verbal deductive reasoning in the Indonesian context, thus providing a relevant tool for various deductive reasoning assessment purposes in Indonesian samples.Penalaran deduktif merupakan inti dari rasionalitas dan salah satu komponen utama yang menggambarkan tingkat kecerdasan, namun alat ukur penalaran deduktif di Indonesia memiliki akses yang terbatas dengan properti psikometri yang tidak dipublikasikan. Penelitian ini bertujuan untuk mengembangkan alat ukur penalaran deduktif yaitu General Sequential Reasoning-Verbal (GSR-V) dan meneliti kualitas psikometrinya (reliabilitas, validitas, struktur faktor). Penelitian dilakukan secara cross-sectional dengan partisipan 163 siswa kelas 10-12 dari beberapa SMA di Indonesia yang diperoleh melalui teknik convenience sampling. Alat ukur terdiri dari dua jenis tugas, yaitu silogisme dan kondisional. Pengambilan data dilakukan secara daring. Data dianalisis berdasarkan tingkat kesulitan dan daya pembeda item, reliabilitas, analisis faktor konfirmatori (CFA), serta analisis validitas konvergen. Diperoleh hasil bahwa 20 item GSR-V dapat diandalkan dan memiliki struktur dua faktor (silogisme dan kondisional) dengan kesesuaian model yang memadai. Selain itu, analisis validitas konvergen menunjukkan bahwa GSR-V memenuhi standar reliabilitas komposit dan muatan faktor, namun nilai average variance extracted (AVE) belum memadai. GSR-V terbukti cukup reliabel dan valid dalam mengukur penalaran deduktif secara verbal dengan bahasa Indonesia, sehingga relevan digunakan untuk berbagai keperluan pengukuran penalaran deduktif pada sampel Indonesia.]]>
