Final answer:
The most common situation for which the main parameter of interest is a population proportion is assessing the percentage of voters supporting a candidate, as it involves estimating the qualitative measure of voter support that falls into two categories.
Step-by-step explanation:
The most common example of a situation for which the main parameter of interest is a population proportion is c) Assessing the percentage of voters supporting a candidate. When dealing with a proportion problem, the data collected is categorical and can be dichotomized into two categories such as Yes or No, Success or Failure. In the context of assessing voter support, one would be estimating what proportion of the voting population supports a given candidate, which is a qualitative measure of data and ideal for proportion analysis.
For instance, a political party may conduct a survey to determine the proportion of voters in favor of their candidate or a specific cause. This kind of analysis can be used to construct a confidence interval for the true population proportion, utilizing procedures similar to those used for population means. However, the population proportion confidence intervals employ different formulas, adhering to the same underlying statistics principles.