Tag: Measure

Measures – Year Over Year Percent Change
This tutorial is a variation on the month to month percent change tutorial. This specific exploration in year over year performance was born out of reviewing my google analytics information. The specific analysis question I am trying to answer is, how did this current month of website visitors compare to the same month last year. For example I want to compare the number of visitors for November 2016 to November 2015. Did I have more users this year in this month or last year? What was my percent changed between the two months?

Here is a sample of the analysis:

let’s begin with loading our data and data transformations. Open up PowerBI Desktop, Click the Get Data button on the Home ribbon and select Blank Query. Click Connect to open the Query Editor. Click Advanced Editor on the View ribbon. While in the Advanced Editor paste the following code into the editor window, click Done to complete the data load.

Note: If you need some more help loading the data follow this tutorial about loading data using the Advanced Query Editor. This tutorial teaches you how to copy and paste M code into the Advanced Editor.
```
let
 Source = Table.FromRows(Json.Document(Binary.Decompress(Binary.FromText("VdDBDcQwCETRXnyOFMAYcC1W+m9jV8BhfH1ygJ9zBr/8CvEaz+DYNL7nDAFjnWkTTNsUbIqnLfyWa56BOXOagy2xtMB5Vjs2mPFOYwIkikIsWd6IKb7qxH5o+bBNwIwIk622OCanTd2YXPNUMNnqFwomp0XvDTAPw+Q2uZL7QL+SC1Wv5Dpx/lO+Hw==", BinaryEncoding.Base64), Compression.Deflate)), let _t = ((type text) meta [Serialized.Text = true]) in type table [#"Start of Month" = _t, Sales = _t]),
 #"Changed Type" = Table.TransformColumnTypes(Source,{{"Start of Month", type date}, {"Sales", Int64.Type}}),
 #"Inserted Month" = Table.AddColumn(#"Changed Type", "Month", each Date.Month([Start of Month]), type number),
 #"Inserted Year" = Table.AddColumn(#"Inserted Month", "Year", each Date.Year([Start of Month]), type number)
in
 #"Inserted Year"
```
While still in the Query Editor rename the query to Data. Then click Close & Apply to complete the data load into the data model.

Load Monthly Data

Next, make four measures. On the Home ribbon click the New Measure button. Enter the following to establish a reference date to the subsequent equations:
```
Date Reference = DATE(2016,12,31)
```
Enter in the following equation to calculate the last year monthly sales amount.
```
LastYear = 
  VAR 
    CurrentDate = [Date Reference]
  RETURN
    CALCULATE( 
     SUM(Data[Sales]), 
     Data[Year] = YEAR(CurrentDate)-1
    )
```
Note: Using the NOW() function calls the current time when the query was last run. Thus, if you refresh your data next month the NOW() function wrapped in a YEAR() will return the current year from the date-time observed by PowerBI.

Following the same process enter the following additional measures. The ThisYear measure calculates the sales for the current month.
```
ThisYear = 
  VAR 
   CurrentDate = [Date Reference] 
  RETURN
   CALCULATE(SUM(Data[Sales]),Data[Year] = YEAR(CurrentDate))
```
Finally, add the calculation for the Year to Year comparison.
```
YoY Percent Change = DIVIDE([ThisYear], [LastYear], 0)-1
```
Since the YoY Percent Change is a real percentage we need to change the formatting to a percent. Click on the YoY Percent Change measure then on the Modeling ribbon click the % symbol in the formatting section of the ribbon.

Change Measure Format

Next, add a Stacked Column Chart with the following columns selected.

Add Stacked Column Chart

OK, we have a chart, but it is kinda awkward looking right now. The x-axis is the month number but we don’t have a month 0. That simply does not make sense. Let’s change some of the chart properties. While having the Stacked Column Chart selected click on the Paint Roller in the Visualizations pane. First, click on the X-Axis and change the Type to Categorical.

Change X-Axis

Then click on the Data Colors and turn on Diverging. Change the Minimum color to Red and the Maximum color to Green. Set the Center to a value of 0.

Change Colors

Click on the Title change it something meaningful, Center the text and increase the font size.

Change Title

Our bar chart looks much better. However, the month numbers do not look quite right. Visually the month indicators would be cleaner if we didn’t have any decimals. Click on the Month field and then on the Modeling ribbon change the Data Type to Whole Number. There will be a warning letting you know that you are changing the Data Type of the Whole number. Click OK to proceed with the change.

Change Month to Whole Number

Another successful percent change tutorial completed. I hope you enjoyed this year over year month comparison example. Make sure you share if you like what you see.
December 5, 2016
Power BI Histogram with Bins – Includes DAX
Alright to start this Tutorial off right we are going to incorporate the new feature released this spring from Power BI, called publish to web. Below you can view last weeks tutorial and interact with the data. Feel free to click around to see how the visualization works (you can click the shaded states or on the state names at the bottom.

For this tutorial we will build upon the last tutorial, From Wikipedia to Colorful Map. If you want to follow along in this tutorial click on the link and complete the previous tutorial.

Materials:
- Power BI Desktop (I’m using the March 2016 version, 2.33.4337.281) download the latest version from Microsoft Here.
- Mapping PBIX file from last tutorial download Maps Tutorial to get a jump start.
Picking up where we left off we have data by state with data from the 2010 Census and 2015 Census.

Data from Region Maps Tutorial

What we would like to identify is how many states are within a given population range. Say I wanted to see on the map, or in a table all the states that had 4 million or less in population in 2010.

To do this we will create bins for our data. Enter custom data in this format. For the tutorial on entering custom data into Power BI Desktop check out this tutorial on Manually Enter Data. Click on the Enter Data button on the Home ribbon. Enter the data as following:

Enter Bucket Data

Note: Make sure you name the new table Buckets as shown in the image above.

Click Load to bring the data into the data model. Notice we now have a new table in the Field column on the right.

Buckets Table

Next we will create a measure to evaluate the state level data into our newly created buckets. This will be produced using DAX (Data Analysis Expressions). DAX is an extremely powerful language which is used in SQL applications and Analysis Services. More information can be found on DAX here. Since DAX is so complex we won’t go into a full explanation here. However, we will have many more topics in the future working on and building DAX equations.

Click the Ellipsis next to the table labeled US Census. Then click the first item in the list labeled New Measure.

Note: Ellipsis is the term used for those triple dots found in newer Microsoft applications.

Example of Ellipsis

A formula bar opens up underneath the ribbons bar. Here is where we will name and type in the new measure. The equation we will need to add is the following.
```
Bins = CALCULATE(COUNTROWS(FILTER('US Census',and([2010 Census] >= min(Buckets[Min]),[2010 Census] <= MAX(Buckets[Max])))))
```
Press Enter to enter the measure into PowerBI.

Explanation of Equation: All text before the equal sign is the name of the measure. All the data behind the equal sign is the DAX expression. Essentially this equation is calculating the number of rows where we have data between the Buckets “Min” value and Buckets “Max” value. This is the magic that is DAX. In this simple expression we can compare all our data against our buckets ranges we made earlier.

Finally our new Bin measure should look like the following.

Bin Measure Created

Now lets modify our visuals to incorporate the new Bins measure. Click on the existing map on the page. Remove the % Change item from the Values selection. Add the Bins Measure to the Values section. Notice the map changes color. Next, add the Name field from the table called Buckets into the Legend field. Our map should look similar to the following:

Map with Bins Added

Next Click on State, 2010 Census, Bins, and Name (from Buckets table) and make a table. It should look like the following:

Table of Bins Measure

Lastly, we will build a bar chart using our Bins Measure. Click on the Stacked Column Chart Visual and add the following items to the corresponding categories: Axis = Name (from the Buckets table), Legend = Name, and Value = Bins (from US Census table). This will yield the following visual.

Bins in Bar Chart

Click on the Ellipsis of the bar chart and then click Sort By, finally click Bins. This will order the items in descending order by the count of the items found in each bin.

Now have fun with your new data. Click on each of the bars in the bar chart and watch your data transform between the table, and the map.

Selection Big in the Bar Chart

Here is the final product if you want to engage with the data.

I have to give credit where credit is due. Below is the page from Power Pivot Pro that I used to create binning in the tutorial chart. The binning shown on PowerPivotPro is for Power Pivot but the functionality is the same. Enjoy.

http://www.powerpivotpro.com/2015/03/creating-a-histogram-with-a-user-defined-number-of-buckets/

Want to learn more about PowerBI and Using DAX. Check out this great book from Rob Collie talking the power of DAX. The book covers topics applicable for both PowerBI and Power Pivot inside excel. I’ve personally read it and Rob has a great way of interjecting some fun humor while teaching you the essentials of DAX.
April 27, 2016

Tag: Measure

Measures – Year Over Year Percent Change

Power BI Histogram with Bins – Includes DAX