During the period from 1872 to 1899, social science research consolidated quantitative measurement as a central tool. Researchers pioneered systematic data collection and statistical reasoning, giving rise to psychometric experiments, standardized mental testing, and the quantitative study of intelligence and aptitudes. At the same time, descriptive ethnography and theories of habit formation advanced the analysis of social organization, culture, and learning, fostering closer integration of measurement with field-based observation. Methodological pluralism emerged, as investigations combined numerical analysis with qualitative description to explain behavior, social structure, and cross-cultural variation.