Every visualization in Tableau has a “level of detail”. Understanding this aspect of your analysis and how to control it will make it easier to get to your desired result.
Hi, this is Ryan with Playfair Data TV, and in this video we’re going to talk about an important concept that’s a part of every data visualization, whether you know it or not, as well as talk a little bit about a fifth marks card that we did not talk about in the last video. The topic we’re going to be discussing is called level of detail. Every single chart that you build in Tableau has what’s called a level of detail. To help illustrate this, or at least give you the introduction to this, I’m going to start by just making a quick scatter plot that looks at sales by profit. So I just double-clicked on each of those two measures. The default for Tableau when you do that is to create a scatter plot, which is the name of this chart we’re looking at now.
You can see in the top right corner of this chart that there’s just one mark so far. I’ll change my mark type to circle, and make that mark a little bit bigger so that we can see this a little more clearly. But as you can see, we’ve only got one circle on the entire view. What that circle represents is the combination of sales on the y-axis and profit on the x-axis for the entire file. We’re using the sample superstore data set that comes with Tableau, which has 9,994 records. So what this one circle represents is the sum of sales for those 9,994 records by its sum of profit for those same records.
We only see one circle because we haven’t specified anything more granular than the entire file. Any time you add a field to the marks shelves, column shelf, row shelf, essentially, if you add another breakdown to the view, you’re changing the granularity of that view. And Tableau’s term for that is the level of detail. One of the ways that you can change the viz level of detail is by putting something onto the detail marks card. So if I wanted to break down this one circle by the dimension called category, I could drag category to detail, and now you see three circles instead of one. We’ve changed the viz level of detail from the entire 9,994 records to category. We’re making our analysis more granular.
I could take this a step further and break it down by customer name. I could put customer name on detail. And now we’ve got 2,182 circles on the view. And I know that, by the way, because Tableau has a nice– similar to Excel, there’s a little summary in the bottom left corner of the authoring interface that’s telling me how many circles are on the view. 2,182.
But the point is, we just made our analysis even more granular. We started at the entire file level. We then broke it down by category, which gave us three circles instead of one. We’re now breaking this down by customer name as well as category. So that’s what broke this out even further into these over 2,000 different circles.
But this will be a really important concept for you to know. It’s related to a lot of the different technical features that we’re going to be discussing in other videos. For example, when we do a calculated field, by default, those calculations are going to happen at the viz level of detail, which we just talked about. Over on the advanced track, we’ll also talk about a syntax called level of detail expressions, which will allow you to have multiple levels of detail within the same view. But for now, this has been Ryan with Playfair Data TV – thanks for watching!