An employer wanted to determine the importance of health insurance as a benefit to employees. Which sample is least likely to be biased by personal interest?
◦ A group of 30 employees from the company who had medical treatment in the past year
◦ A group of thirty potential employees at the state office of employment
◦ A survey of 300 union members conducted by the union that represents workers at the company
◦ All of the groups have potential bias.