I am learning a bit more Level of Details(LOD) in Tableau 9 every day. My question has been what it does more to our calculations and analysis? It seem we can do a lot without LOD. Maybe it's just the convenience of using Fixed/Include/Exclude to create aggregations? The formulas becomes shorter and more compact?

My biggest question remains: what can LOD do that we can't do without LOD? What makes LOD absolutely necessary? Anything LOD can do 10x or 100x better than what we have got?

Oh LOD, you see, I have had quite a few doubts and questions.

Simply put, it took a bit of time for me to appreciate the power of LOD.

Recently I got some answers. I am going to use my favorite topic "Histogram" to present my findings.

Histogram is a simple and popular analysis method. Yet its calculation has never been straightforward. If LOD can make histogram's calculation better or easier or clearer, then it will be beneficial to a lot of people. Otherwise LOD may not be worth it. If it is only applicable to some exotic calculations, it is not that useful either.

Histogram via LOD

I will use the same data set as in
Histograms on Aggregated Measures without Table Calculations

Step 1. Create a calc field [Item Count via LOD] and drag it to Columns and turn it into Discrete:

• {FIXED [Customer Name]:SUM([Number of Records])}

Step 2. Right click [Customer Name] and drag it to Rows. Select Count Distinct at popup.
Step 3. Drag [Item Count via LOD] to the Label shelf.

And it's done. This is quick, isn't it?

Not so quick to the conclusion yet. In this method,
Histograms on Aggregated Measures without Table Calculations
We don't need to create any calculated field. We can do it all by mouse.

In this method via LOD, we have to do some coding to create a calculated field. I don't see the benefit of using LOD here.

Tableau 9 natively supports creating uniform bins on LOD aggregations. But we can do it without LOD, albeit a bit tedious. I don't think it's a big advantage. It's a convenience at most.

So what's the big deal about LOD?

The big deal runs deeper than I thought. Here I am going to use a couple of examples to illustrate.

Example 1. Drill-Down

We have multiple ways of creating histograms using Tableau before LOD. But none of the histograms thus created, can facilitate drill down. That is, we are not able to view the underlying data in each bar.

Now with LOD, we can do the drill down. In this example, we need to find out the number of customers per the number of purchased items.

To illustrate, let's create a details worksheet with a few columns. Then create a dashboard and create an action for histogram bars to filter the details.
The workbook can be downloaded here.

Example 2. Stacking Multiple Histograms 

...over the same bins of course.

Recently there is a post in Tableau forum asking to tally up the occurrences of numbers (1-59) in multiple PowerBall lottery drawings, over different dates from 2004 to 2015. In each drawing, there are 5 numbers drawn out of 1 to 59.

The requirement means to create histograms (occurrences of the 59 numbers) for the first drawn number, the second drawn number up to the fifth drawn number. So there are 5 histograms to be created.

Creating those histograms individually is not a problem.

• {FIXED [First number]: COUNTD([Draw Date])}

Histogram via Size()
Histogram via Rank Functions
Binning Aggregates for Histogram and Aggregate Distributions
Dynamic Histogram Over Time
Histograms on Aggregated Measures without Table Calculations

So much honored and flattered that my Turing Award Viz is named one of "The Chosen of the Chosen" in Tableau's April Viz Roundup.
It's amazing that Tableau's blog is published in 8 languages. And one thing is sure that they are not using Google Translate. I tested it by using Google Translate to translate the English version to French. The output is like garbage.

The translation of "the Chosen of the Chosen" in most languages is straightforward, ie, Google Translate can do it. However, Chinese translation "精品中的精品" means "The finest of the finest". My favorite expression is in French "La Crème de la Crème" or "The Cream of the Cream". Not surprising for a people deeply in love of gastronomy.

In addition, this article has been selected to be the Best of Tableau Web April 2015:
Dynamic Histogram over Time

I am very grateful to the Tableau community for inspiration and encouragement!

I have written a blog on the same topic a while ago, based on creating sets. The sets approach is good when no filter is in action. The approach described here can be more general.

This is a companion post to Grouping Lower Ranked Bars in Bar Chart. We will use most of the same calculated fields.

Step 1. Create an integer parameter [Top N].

Step 2. Drag [Country / Region] to Details shelf and sort it by Sum(Sales) in descending order.

Step 3. Create a [Top N+1 Rows] filter:

• Index()<=[Top N] +1

Drag it to Filters and set it to Compute using> [Country / Region]. Select True at pop up.

Step 4. Select mark type to be Pie chart.

Step 5. Create [Top Countries & Others]. This will alias the country at the (N+1)th position to be "Others". Drag it to Color shelf and Label/Text shelf and set it to Compute using> [Country / Region].

• If Index()=[Top N] +1
• Then "Others"
• Else Attr([Country / Region])
• End

Step 6. Create [Top Sales & Others]. At the (N+1)th position, the value is altered to be an aggregated result. Drag it to Angle and set it to Compute using> [Country / Region].

• If Index()=[Top N] +1
• Then Window_Sum(Sum(Sales),0,Last())
• Else Sum(Sales)
• End

Note that in the above formula, the If statement sets the index=0 for the window function which has its own index. The settings here instructs the window function to compute from (N+1)th row to the last row.

That's it! The workbook can be found here.