Peer group pressure is best defined as:

Peer group pressure is best understood as the effect of the social group you belong to, which can significantly influence your behaviors, attitudes, and decisions. This concept is rooted in social psychology, where individuals often look to their peers for cues on acceptable behavior or norms. As a result, the desire to fit in or conform to group expectations can lead to changes in individual decision-making, whether that pertains to lifestyle choices, consumption patterns, or interpersonal interactions.

In this context, a person's social group—whether composed of friends, classmates, or colleagues—plays a pivotal role in shaping their opinions and actions. This encompassing influence can manifest in various ways, such as encouraging specific health behaviors or prompting participation in group norms that may not align with one’s original beliefs. This understanding of peer group pressure is crucial in fields such as public health and economics of health care, as it can help explain why individuals might make certain health-related choices based on group dynamics rather than their independent values or information.