What Is DAX

Data Analysis Expressions (DAX) is a formula expression language that makes it easy for you to perform calculations and queries with your data. This article will explore what DAX is, common function types you might benefit from, advantages and disadvantages to consider, and steps to begin learning.

What is DAX used for?

You can manipulate and understand your data using DAX with several Microsoft products, such as Power BI, Analysis Services, and Power Pivot in Excel. The formulas in this software include functions, operators, and values, each of which works to help you perform different tasks.

When using DAX, you can choose between several types of premade functions, including those meant for common tasks such as aggregating data, calculating values based on dates and times, and completing mathematical functions, logical functions, and functions to manage relationships between variables and text entries. If you don’t find the function you need, you can use the formula bar in DAX to create a custom formula suited for your data types.

Types of DAX functions

You can choose from a wide array of DAX functions depending on your needs. A few of the available categories you might choose from include the following. 

Aggregation functions:

When you use aggregate functions, you will get a numerical value returned after performing a function for all of the data in a single column. Some common aggregate functions you might use include: 

• SUM adds up all the numbers in a column, providing a total sum. If you wanted to know the total sales over a given period, this would be a great function to choose.

• AVERAGE calculates the mean of the numbers in a column. For example, if you wanted to find the average temperature over a one-month period, you could use this function. 

• COUNT tallies the number of non-blank values in a column, such as the number of sales transactions.

• MAX and MIN return the maximum or minimum value in a column. This function would tell you if you wanted to know the biggest or smallest purchase you made over the previous year.

Date and time functions: 

If you are dealing with date and time data, these functions are designed to be helpful to you. They’re similar to the type of functions you might find in Excel, but the formatting of the expressions is slightly different.

• CALENDAR creates a table containing a single column of date values, starting from a specified start date to an end date. This could prepare your data for further time analysis.

• YEAR, MONTH, and DAY extract the year, month, or day part from a date value, which might help you break down dates for analysis by time periods.

• DATEDIFF finds the difference between two dates. You could use this function to calculate things like age, trimester of pregnancy, or duration between events.

Statistical functions: 

For more complex operations, you can use statistical functions to find out details about your data’s distribution and probability. A few statistical functions you might find useful include:

• CHISQ.DIST computes the cumulative distribution or probability for a supplied chi-square value and degrees of freedom used in hypothesis testing or statistical models.

• COMBIN determines the number of possible combinations for a given number of items, which is useful in statistical analysis involving combination counts.

• BETA.DIST returns the beta probability distribution, a function you might use for project planning and quality management to model probable completion times.

Text functions: 

Text data requires a different type of analysis than numerical information, which is where text functions come in. If you are dealing with string (text) values, you can rely on the following functions: 

• EXACT compares text strings to see if they are the exact same, which is useful for matching products with models in your inventory.

• UPPER and LOWER change text strings to all uppercase or all lowercase, which is useful for standardizing text data for comparisons or display.

• CONCATENATE merges two or more text strings into one. If you had first and last name strings, you could combine them to make one full name string.

• FORMAT converts value to text string according to specifications you set.

Logical functions: 

Logical functions return information about your values, allowing you to perform more specific operations and calculations. 

• IF evaluates a condition and performs different functions based on whether the input is true or not.

• SWITCH offers a more streamlined alternative to nested IF statements by evaluating a series of conditions and returning the corresponding result for the first true condition.

• OR and AND perform logical disjunctions or conjunctions. OR allows you to perform functions if only one condition is true, while AND ensures you only perform tasks when all values return true.

• TRUE simply returns the logical TRUE value, often used within more complex logical conditions or checks.

• LEFT and RIGHT return the leftmost or rightmost characters of the string. You could use this to return a first or last name from a full name string.

Who uses DAX?

Professionals without a strong background in data science and analysis can use DAX to perform calculations on their data. This software is designed for different types of analysts, business intelligence professionals, and developers, allowing the use of a mix of built-in and customized functions. 

Because DAX is used with Microsoft products such as Power BI, you may see DAX  used in industries that commonly work with this software:

• Finance: In finance, DAX helps analyze financial data, assess risk, and forecast to make informed investment decisions. Specific financial functions help professionals in this industry gain insights.

• Retail: Retail professionals can use Power BI (and DAX) to track sales performance, customer trends and segmentation, and inventory levels to optimize stock and improve customer satisfaction.

• Human resources: Power BI allows for tracking of hires, potential biases, trends in hiring, and modeling of employees across departments. Professionals in this space can use DAX functions to work with their data and enhance insights.

Pros and cons of using DAX

DAX is an exciting tool for data analysis, and being aware of the advantages and disadvantages can help ensure you get the most benefits from this program. While advantages and disadvantages will be unique to every user, some common ones are as follows.

Advantages:

• Many pre-built functions: DAX offers many functions for professionals with varying data needs.

• Integrates with Microsoft products: Due to its ability to integrate with several platforms, DAX is a versatile choice for data analysis.

• Real-time updating: You can create dynamic values that update as your data changes so your insights are accurate.

Disadvantages:

• Requires finding formulas specific to your data: In some cases, your data format might not work naturally with intended functions. If so, you have to design your formula or find a different one to perform your action.

• Can take time to learn: Like any language, DAX takes time to learn, so we recommend using available resources and building skills over time. If you need to perform advanced data manipulation, crafting efficient DAX queries can become complex, especially when building your own functions. 

How to start learning DAX

Since DAX is primarily used within Power BI, Power Pivot for Excel, and Analysis Services, gaining a solid understanding of these platforms can help you more effectively use this language. You can start learning by:

• Taking online courses and tutorials

• Reading through online blogs and resources such as the DAX reference

• Practicing with data on independent projects to enhance understanding

• Reaching out to professionals with shared interests and creating a support network 

Get started with Coursera.

You can take courses tailored to DAX and Microsoft Power BI on the Coursera learning platform. For a broad overview of Power BI, including a specific introduction to DAX, consider the Microsoft Power BI Data Analyst Professional Certificate offered by Microsoft.