This article develops an econometric framework to formalize the determinants of consumer behavior and to quantify their effects on purchase decisions and consumption volumes. The analysis systematizes key drivers such as income and income uncertainty, prices and inflation expectations, household socio-demographic characteristics, access to information and digital channels, marketing exposure, and behavioral factors (trust and risk preferences). Methodologically, the study employs discrete-choice models (logit/probit) to estimate purchase probabilities, regression and panel data specifications (fixed/random effects) to model demand intensity, and strategies to mitigate endogeneity (instrumental variables and robustness checks). The proposed formalization supports evidence-based consumer policy design, market monitoring, and evaluation of interventions aimed at improving market transparency and consumer welfare.