If the question was: What is an optician's revenue per year?
Can you start with clarifying questions as you would in other cases? (E.g. where is the optician located, what is the population of the town, is the distribution only in stores or also online?)
How do you lay out the structure? I could think of several ways, but is there a right or better one? (E.g. you could start by identifying the different revenue streams and then add them together in the end, you could identify the customer base and then multiply them by the average purchase of a customer) -> What is the bottom up approach to this?
How detailed should a segmentation be? I tend to segment too much, get tangled up, loose my structure and take a too much time. (e.g. if I would think about the revenue generated by glasses, I first go from population of town -> devided by number of opticians in town -> think about percentage of how many have problems with their eyesight (I could segment by age and argue that children and youth tend to have a lower percentage and older generations have a higher percentage of people with eyesight problems) -> percentage of people actually wearing glasses( how many of them would wear glasses and how many wear contactlenses, although I think people with contaclenses also have a pair of glasses) -> then I could also think that some people have more than one pair especially older people tend to have two because they need one pair as reading glasses and the other pair for everyday life -> then I would have to think about how often people replace their pair of glasses (maybe every 2-4 years?) and divide the customer base by this number, because we are looking for a per year revenue -> and then finally multiply by the average price of a pair of glasses...
This is only for one revenue stream, but what can you do to give it more structure and when do you stop going too much into detail and segmenting too much?
Thank you very much,