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February 6, 2017

Makeover Monday: Are We Nearing the Death of Chicago Taxis?

Now THIS was a fun week! Eva and Exasol set us up with 105M records to play with. Often time, this can feel like an incredibly daunting exercise, but I took a very methodical approach. More about that in a minute. First, let's take a look at the viz we want to makeover:

What works well?

  • Using a line chart to portray a time series rarely is a bad choice
  • Nice simple labeling of the axes
  • Title tells me what I'm looking at
  • Red line on the grey background works well
  • The y-axis is truncated, but the chart maintains a nice 3x2 ratio so that the line trends aren't too distorted.

What could be improved?
  • Scale of the y-axis is a bit odd; I like nice rounded numbers that make the math easy to do in my head
  • There is SO much more data to work with; why limit to only trips?
  • Could use a more impactful title
  • Could use more context

This week I decide to apply some of the training we received from Rhiannon Fox and do a bit of mood boarding, color choosing and seeking overall inspiration. I knew I wanted to create a summary dashboard of sorts that included lots of context, so after a bunch of Google image searching and pinning, I ended with this mood board.

I started by connecting to all 105M records live because I wasn't sure which dimensions I would end up using. When I finally finished (this took well over an hour), I created an aggregated extract. The trick to this is to hide the dimensions you aren't using before you create the extract and to rollup to the lowest date level in the view (month for my viz). This took the viz from 105M to 299K records. Incredibly, the extract was ready in less than 10 seconds. Exasol is crazy fast!

Overall, another fun week. Tonight I get to introduce this to a bunch of new Tableau users at the #MakeoverMonday Live session at Tableau HQ in London. Can't wait to see what they come up with!


  1. Great work, Andy! Could you walk me through the Dot Color calc though? I can't wrap my head around that one.

    1. You can download the workbook and see how it works. Or did you do that already and just need a plain English explanation?

    2. That's what I'm needing, I think. My understanding is that it serves as a boolean test that will only return a result if the record is either the first or last month, but I'm not sure how it works. My first thought was you could just use a LAST()=0 calculation, then put it on color. It would work fine for a dual axis line, but that would show a point at each month (which would be crowded in a sparkline).

    3. Correct, it's a boolean test. I can then write another calc to do something else based on the result of the boolean.

  2. Hi Andy :),

    First of all I'm a big fan of yours work. Dashboard looks awesome.
    I have one question - after digging into calculations (i always learn something new from yours dashboards) i believe that Dot Color field is now working as should. We always will see false value because "Last value" < 0 Example is MOUNT GREENWOOD
    I added exclude to duplicate data in second calculation.

    IF LAST()=0 THEN
    SUM(IF {MAX(DATETRUNC('month',[Trip Start]))}=DATETRUNC('month',[Trip Start])
    THEN [Trips] ELSE 0 END)
    <sum({ EXCLUDE DATETRUNC('month', [Trip Start]) :
    SUM(if [Last Month Prev Yr?] THEN [Trips] ELSE 0 END) })

    Could you please verify if I'm thinking correct or maybe I missing something ? :)