Final answer:
The number of subjects for commercial advertisement testing varies based on study goals, variability in responses, and needed statistical power. It can range from small controlled studies to larger samples that represent the wider population. The key is balancing representativeness with the practicality of conducting the study.
Step-by-step explanation:
The number of subjects required for commercial advertisement testing involving physical factors can vary depending on the objectives of the study, the expected variability in responses, and the statistical power needed. For instance, an initial hypothesis testing may enlist 24 participants, dividing them into two groups of 12 for a controlled study. However, larger samples such as those involving 212 businesses in a recycling study or polls of 1,200 phone numbers for voter reaction to a debate provide a more representative and reliable measure of the wider population's behaviors or opinions.
In a practical sense, samples for commercial advertisement testing should be large enough to achieve representativeness and to detect the effect size anticipated by the researchers, but also manageable in terms of resources and time. For example, sampling every tenth person entering a store or the first 50 attendees at an event may give a quick snapshot of consumer preferences, but it might not be representative of the entire target audience.