To obtain reliable, valid marketing research data when conducting personal interviews, researchers must ensure that the interviewers are which of the following?

The effectiveness of personal interviews in marketing research significantly relies on the demeanor and behavior of the interviewers. When interviewers are open, friendly, and nonjudgmental, they create a comfortable environment for respondents. This openness fosters trust, enabling respondents to share honest and candid insights without fear of judgment or backlash. A friendly demeanor encourages engagement, making respondents feel valued and respected, which can lead to more in-depth and quality responses. Being nonjudgmental is crucial as it allows for a better understanding of the respondents' perspectives, thus ensuring that the data collected is both reliable and valid. When interviewers embody these characteristics, they are more likely to gather comprehensive and accurate information, vital for effective marketing research.