Yelp has an a block of ads on the top of the page. How would you define the optimal number of ads to show to users.

The question aims to assess your capability in finding a balance between business goals and user's experience. The business objective here is to maximize advertisement revenue, but coming from a user experience perspective, too many ads can have a negative impact on the user experience. It's crucial that you demonstrate an understanding and consideration for both sides when crafting your response. Another critical point to highlight here is that you are able to think about this problem scientifically, suggesting experiments, metrics to track, etc.

We want to optimize the number of ads based on our company's goals of maximizing revenue while also maintaining a positive user experience. Hence, my first step would be to conduct an A/B test. We could create various versions of our page that show differing numbers of ads – for example, one with 3 ads, another with 5, and another with 7. We then expose each group of users to different versions of the page and track the relevant metrics. These could include bounce rate, time spent on the page, click-through rate (CTR) on the ads, and ultimately, the revenue generated from ads. By analyzing these results, we can identify the optimal number of ads that maximizes revenue while not significantly impacting bounce rate, or the time spent on the page. This is a technique we can continue to use as we refine and improve our product.

To determine the optimal number of ads, we need to consider more than just revenue – user experience is equally important. Therefore, while we need to display ads for monetization purposes, we also want users to interact positively with our site.

To achieve this balance, we can leverage data and user feedback. We start by experimenting with various numbers of ads to see which one works best. For instance, we can use machine learning algorithms to dynamically adjust the number of ads shown to users, based on their interaction with the site.

We should also regularly survey users to gauge their sentiment about the number of ads, allowing us to tweak our display strategy based on direct feedback.

Furthermore, we need to monitor key metrics like, bounce rates, session duration, interaction with the ads, etc. A high bounce rate and low session time might mean that the number of ads is too high for most users. By continuously monitoring these metrics and iterating our strategy accordingly, we can optimize the number of ads displayed."