Astudy examined the personal benefits for businessmen of making a higher salary. in the study, the researchers investigated the link between yearly salary and personal happiness (measured on a 7-point scale where 1 = "very unhappy" and 7 = "very happy"). participants for the study were those who used a popular web site for business networking. the web site's directory was searched for those with "average" names (e. g. "john smith", "sara jones"). these individuals were then invited to participate in an online survey in exchange for a dollar 20 gift certificate. of the respondents, those who made very high or very low salaries were excluded, leaving a sample size of 50 respondents. answer parts (a) through (d) identify the experimental units for this study. choose the correct answer below. businessmen who used a particular web site salaries of businessmen personal happiness levels all businessmen what are the variables of interest? are they quanititative or qualitative in nature? salary, qualitative: happiness level, quantitative salary, quantitative; happiness level, qualitative salary, quantitative; happiness level, quantitative salary, qualitative; happiness level, qualitative describe the population of interest. choose the correct answer below. all businessmen businessmen who used a particular web site personal happiness levels salaries of businessmen do you believe the sample of 50 respondents is representative of the population? explain. yes, an average subset of the population was obtained, and anyone within this subset could participate. yes, since the web site is popular, the sample is likely to contain a diverse group. no, although an average subset of the population was obtained, the group within this subset that participated was self-selected. no, selection bias is present since only those with "average" names could participate, and the group of these that did was self-selected.