A sociologist is conducting a study to analyze the effects of a new public transportation system on low-income families' access to job opportunities. They decide to use a mixed-methods approach, incorporating both surveys and participant observation. Given this scenario, which aspect of research design is most critical for ensuring the reliability of their findings?

In this study, the most critical aspect of research design for ensuring the reliability of findings is the way data is collected and analyzed. The sociologist needs to ensure that both the surveys and participant observations are designed carefully to capture accurate information about low-income families' experiences with the new transportation system. For instance, if the surveys are poorly worded or biased, the results might not reflect true opinions or experiences, leading to unreliable conclusions. Additionally, consistent methods in participant observation, such as how often and in what settings the observations are made, are essential to gather valid insights. By focusing on these aspects, the sociologist can strengthen the overall reliability of their study.