#### Overview of this book

The Tableau Desktop Specialist certification is fundamental for any data visualization professional who works in the field with Tableau. This book gets you started by covering the exam format, Tableau basics, and best practices for preparing data for analysis and visualization. It also builds on your knowledge of advanced Tableau topics to get you up to speed with the essential domains and domain objectives. Although the guide provides an outline and starting point to key in on what needs to be understood before the examination, it also delivers in context to give you a strong understanding of each piece before taking the exam. Instructions on how to get hands on with examples, a common data source, and suggested elements are also included. Understanding the concepts will not only assist you in passing the examination, but will also help you work effectively with the tool in your workspace. By the end of this book, you'll be able to efficiently prepare for the certification exam with the help of mock tests, detailed explanations, and expert advice from the author.
Preface
Part 1: Introduction to Tableau
Free Chapter
Chapter 1: Tableau Desktop Specialist Certification Overview
Chapter 2: Data Ingestion
Chapter 3: How to Interpret Data in a Tableau Visualization
Chapter 4: Working with Dimensions, Measures, and Marks (Oh My)
Chapter 5: Calculations and Functions Syntax
Part 2: Mastering the Exam
Chapter 6: Connecting to and Preparing Data
Chapter 7: Understanding and Creating Fundamental Charts in Tableau
Chapter 8: Data Organization and Worksheet Analytics
Chapter 9: Sharing Insights
Part 3: The Final Prep
Chapter 10: Exam Preparation
Chapter 11: Mock Test
Index
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# Introduction to LOD expressions and parameters

LOD expressions and parameters are some of the most powerful yet least understood elements for newer Tableau users. We will go a little deeper into these concepts in future chapters but want to make sure you are introduced to the very basics in this section.

## LOD expressions

LOD expressions show up as standard calculations and can be included as part of a standard calculation. The purpose of LOD calculations is to create a measurement at a defined level of aggregation. When creating most calculations, the LOD is dependent on what is in the workbook, defined details, or filters. There are three LOD calculations (Fixed, Include, and Exclude) to help independently define the details seen on the visualization that we will look at in the following list. Please review the Order of operations section to see how filters and other pieces impact your visualization.

• Fixed—This is a LOD expression that looks at the referenced dimension...