Propensity score matching is a statistical technique used to reduce bias in observational studies. It involves pairing individuals from different groups based on their likelihood of receiving a treatment, known as the propensity score. This score is calculated using observed characteristics, ensuring that the groups being compared are similar in these aspects. By matching individuals with similar propensity scores, researchers can create a more balanced comparison between treated and untreated groups. This helps to isolate the effect of the treatment, making it easier to draw valid conclusions about its impact while minimizing confounding variables.