How can you show the total number of website visitors that used a mobile phone?

Creating a filter expression is the most effective way to show the total number of website visitors that used a mobile phone. A filter expression allows you to focus on a specific subset of your data based on defined criteria. In this case, by applying a filter that captures only visitors using mobile devices, you can calculate the total number of these users accurately.

Filters are critical in data analysis as they refine the data set to improve clarity and relevance. They enable users to derive insights from specific segments of the data, making it easier to understand visitor behavior on mobile compared to desktop or other platforms.

The other options, while useful in various contexts, do not serve the purpose of directly isolating mobile visitors. For instance, creating a rank column might be useful for comparing performance across different segments but does not specifically narrow down the data to mobile users. A hierarchy expression parameter helps organize data but does not filter for mobile visits. Similarly, a restricted column can limit data to certain conditions but is not as straightforward or precise as a filter expression for the task at hand. Thus, using a filter expression is the most direct and effective approach to achieve the desired outcome.