This would leave the respondent unsure that it would take time for him/her to answer the question, and could even lead to an unanswered question in the survey. To account for this uncertainty, the question could be phrased, "Based on what you can recall (or based on your recollection), when did you first start chewing gum?" While the answer could not be accurately true, the response provided would at least be considered as reported/recalled by the respondent. How much discretionary buying power do you have each year?

The term "discretionary buying power" is too complex for the respondent to understand. At best, the researcher could ask the respondent if s/he could provide the percentages or proportion of expenses s/he incur every year, and identify the products or services these percentages/proportions are spent on every year.

Why did you decide to attend Big State University?

While this question is acceptable to ask the respondent, the researcher must also indicate within the question that s/he knows there could be more than one reason why the respondent decided to attend Big State University. The question can be rephrased as follows: "What are the reasons that made you decide to attend Big State University? What else? Anything else?" Probing questions are added to ensure that all possible answers are exhausted from the respondent.

Do you think the president is doing a good job now?

This question can be answered by a simple "yes" or "no." If the researcher is looking for more depth in the respondent's answer than a simple yes or no, then s/he could rephrase the question to, "Do you think the president is doing a good job now? Why? Why else? Anything else?" Probing questions are added to ensure that all possible answers are exhausted...

Since there is no prior data that could give an indication of concertgoers' profiles, the best that the researcher could do using non-probability sampling is to provide a profile of concertgoers surveyed, noting that the profiles would not be representative of the concergoer/viewer population that has attended the concerts/events.
At best, the researcher could implement quota sampling, assigning a 50%-50% split between male and female concertgoers. This 50-50 split is based on the assumption that since the researcher does not have an idea about the male-female proportion in the concertgoer population, it is best to provide an equal split, so that both groups are equally represented in the sample. From this 50-50 split, the researcher could just interview anyone in the concert venue through intercept interviews. In intercept interviews, respondents are identified and surveyed since s/he happens to be at the location or venue in which the survey enumerator or researcher is conducting his/her survey. This 50-50 split will be implemented in every concert or musical event that the researcher will include in his/her survey sample.

However, to establish the percentage of male and female concertgoers in the venue or event, one method is to identify them immediately at the venue entrance. The researcher could assign field researchers who could use clickers and identify whether the incoming concertgoer at the gate is a male or a female. This method provides not only the total number of concertgoers, but also the proportion of males and females who have attended the concert/event. Once the male-female proportion is determined, the researcher could then use this as a basis for interviewing concertgoers based on convenience sampling and intercept interviewing.