Questionnaire bias refers to the systematic error or distortion in the results of a survey or study caused by the design, wording, or administration of a questionnaire. This bias can occur when the questions are phrased in a way that leads the respondent towards a particular answer, or when the sample population is not representative of the target population. It can also arise from the bias of the researcher or the influence of external factors on the respondents’ answers. Questionnaire bias can significantly impact the accuracy and validity of the data collected, making it crucial for researchers to carefully design and administer questionnaires to minimize its effects.