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While I was preparing for my Tableau Desktop certification exam, I decided to go over a topic that went a bit over my head during training, fixed LODs.

LODs (level of detail calculation) are a somewhat advanced topic in Tableau, but they are vital for certain purposes and use cases. They are a way to control how calculations are aggregated. For example:

This is calculating the sum of sales for each category. And when its fixed it doesn’t matter what else is on the view, it won’t break it down further. So it will calculate sum of sales without breaking it down into the sub-category level. This is shown in the below image. On the left is the fixed LOD and the right is sum(sales) by sub-category.

The right is sum(sales) broken down by sub-category, and the left is the sum(sales) fixed at the category level. It shows the total sales for furniture for every sub-category of furniture.

We can see how the fixed sales is the sum of the subcategory sales.

Now that I’ve given a brief description of Fixed LODs, I want to share some links that helped me understand them better.

### Fundamentals of Level of Detail Calculations

Here is a youtube video from Andy Kriebel. I found Andy’s way of putting the calculations into human sentences particularly helpful. He goes through many examples of fixed LODs, even with multiple dimensions fixed. An example is the following:

Andy might break it down something like ‘for each customer name, count the distinct order IDs’. Check out the video, its very helpful.

### Top 15 Tableau LOD Expressions

In this article by Bethany Lyons on the tableau official blog, they provide 15 use cases for LODs, not just fixed but also include and exclude. I recommend following along in your own workbook. I found the cohort analysis example, which used fixed LODs, particularly interesting.

If you need more tips for exam prep, this guide by Jason Hu is very comprehensive, and something I referred to in my study.

`Title Photo by Julia M Cameron from Pexels`