VizWiz

Launch, grow, and unlock your career in data
Showing posts with label Mike Roberts. Show all posts

September 12, 2013

Visualizing statistical significance in survey results

6 comments
My colleagues and I at Facebook had the honor of presenting at the 2013 Tableau Customer Conference alongside Kate Treadwell of Interworks, who was subbing for Mike Roberts. The topic of our talk was "Data Discovery at Facebook: Why Culture & Flexibility Matter for Modern Analytics". We based the session around four of Facebook's company values:
  • Move fast
  • Be open
  • Be bold
  • Focus on impact
During the "Be open" section of the talk, Heather Torres, who leads HR & Recruiting Analytics for us, revealed a method for encoding statistical comparisons of survey results. The basic premise is for a manager to be able to view their survey results compared to the company in total, but also understand the statistical significance of the results. Heather had created something similar to this in her past life at AOL in Excel and she challenged me to build something similar in Tableau. It didn't end up being very complicated, once the data was in the correct format of course.

I need to pause for a moment and thank two Tableau Zen Masters for their help and inspiration.

First, thank you to Jonathan Drummey for his help in getting both the manager and company results into the same view.  Jonathan taught me about Data Source Filters, which I had never used before.  We ended up aggregating the data so that we didn't have to have multiple data sources, but without his help early on, we wouldn't have gotten there.

Second, we need to thank Steve Wexler for his awesome work in visualizing survey results.  We based many of our other reports off of work that he's done.

And now back to our regularly scheduled program...

In order to help aid with understanding, here are some tips for how to read and interpret the results:
  1. The dark bar represents the company in total.
  2. The colored bar represent the chosen manager's results.
  3. The width of the bars represents the statistical variation. The manager bar will always be wider than the company bar because there are less results for a manager, thus more less statistical significance.
  4. The color of the manager bars represents how statistically significantly different they are vs. the overall company results.
  5. If you see a gap between the company and manager bars, then the difference is statistically significant.
  6. You can filter by Manager.
  7. You have three chart types to choose from (more below about them).
  8. You have three sorting options, which allow you to answer different questions depending on what you want to compare.
Note: All of this data has been altered randomized, so it doesn't reflect our actual survey.  The manager IDs are all fake, etc.

The view that Heather showed in our session was the Double Gantt (TM) option.  I've provided two other alternatives as well: Candle Gantt (TM) and Dots Gantt (TM).

The Candle Gannt is more or less the same as the Double Gantt, but the company bar is thinner and there are reference lines for the ends.  The idea here was to make it look somewhat like a candlestick chart.

The Dots Gantt is nice because it clearly shows the outer ends of the statistical range without concern for the range itself.

I had no idea what to call these types of charts, so the names are simply a combination of the chart types (And they aren't really trademarked.  Maybe I should TM them). These are all dual axis charts. Download the workbook and pull the charts apart if you're interested in seeing how they're built.

For those of you that came to our session, we owe you a heartfelt thank you.  We appreciated all of the questions, comments and great interaction.

July 11, 2013

Tableau Tip: If you can’t open a Tableau workbook because of the space on your hard drive, Tableau itself may very well be at fault.

6 comments

The other day I was working on a re-design of a dashboard, taking it from using extracts to using a live connection and making some other design changes that would speed the dashboard up.  Naturally I wanted both workbooks open at the same time so that I could work on the new one while maintaining all of the design of the first one.

The packaged workbook is 1.4GB, which basically never finishes downloading from Tableau Server, so you have to get the original author to give it to you on a memory stick.  That’s another problem for another day.  I opened the workbook and saved it under another name so that I would have two copies.  Great!

Then I need to open the original workbook again so that I could see them together.  Then…POOF!…Tableau couldn’t open the workbook because it said I didn’t have enough space on my hard drive.  Huh?  How can I not have enough space if I was able to save the workbook and I clearly have space on my hard drive?

With a bit of research, I was able to locate a TableauTemp folder I never knew existed. It’s located here: C:\Users\<your_name>\AppData\Local\Temp\TableauTemp

Low and behold, there are tons and tons of folders and files in the folder, which totaled over 16GB.  Seriously!  Go ahead, check yours.

May 2, 2013

Tableau Tip: Creating a primary group from a secondary data source

6 comments

Mike Roberts, our Tableau consultant from InterWorks was helping one of our users last week and sent along a great tip for creating a field in your PRIMARY data source with a field in your SECONDARY data source.

Step 1: Add ‘Helper’ sheet and drag desired field from your PRIMARY source on to the ROWS shelf.

clip_image001

Step 2: Add matching field from SECONDARY data source and nest it next to the existing field on the ROWS shelf.

clip_image002

Step 3: Right-click the SECONDARY field on the ROWS shelf and select ‘Create Primary Group’.

clip_image003

clip_image004

NOTE: make sure you check the Include ‘Other’ check box

Step 4: Verify the group is now in your PRIMARY data source.

That’s it! You no longer need to blend or use the SECONDARY SOURCE field.

There is one gotcha to be aware of: If a record is added to the dimension you’re grouping in the primary data source, a new person in this example, you will have to regenerate the group or the new person will automatically get put into the “Other” group.  Creating a primary group does not dynamically update.