(soft jazz)
- Hello, I am professor Rick Jerz
and I welcome you to this session
titled Tableau-Scatter Diagrams.
In this session we are going to learn
how to produce scatter diagrams using Tableau.
The creation of scatter diagrams
is one of the first steps to simple regression analysis.
I think you are going to enjoy this session.
Let's get started.
I'd like to show you how to create
a scatter diagram with bubbles.
Remember that a scatter diagram
is a two-dimensional representation of two variables.
In Excel, a scatter diagram is very easy to produce.
In fact, Excel provides this tool
to create a scatter diagram.
Let's see how we will do this using Tableau.
We will continue using our real estate date file
that we used in earlier projects.
If you forgot how to load this file into Tableau,
review one of my earlier sessions.
I begin by creating a new sheet.
I will rename this sheet to Scatter Diagram.
Let's say that we are wondering whether or not
the price of a home is dependent upon the size of the home.
In this case the size of the home
will be our independent variable
and the price be our dependent variable.
I drag the size measure to columns and the price to rows.
Hm, so far, I don't see a whole lot happening.
The one dot that shows represents
the total size of all homes.
We want to split this out to individual homes.
So what I need to do is to drop down this right arrow
on the size and switch this over to dimension.
Now it's looking a little bit better.
We have a line chart and I really want to see this as dots.
So I just change the mark type from automatic to circle
and my scatter diagram is complete.
However, I do notice one thing.
The price dimension shows sum
and what I am really interested in
is whether or not the average price
of the home depends upon its size.
So I have to change this sum to average.
Now this is looking a little bit better.
The beauty of Tableau is that it is able to show
more than two characteristics on these scatter diagrams.
In fact, we could show three, four,
or maybe even more dimensions on a 2D chart
by using size and color.
So let's say we are wondering whether or not
more expensive homes tend to have more bedrooms.
I will begin this exploration by duplicating
this scatter diagram sheet
and calling it Scatter Diagram w Bubbles.
Then I drag the bedroom dimension over to the size icon
and I will change the size of this
to something that looks pretty good.
When I look at this diagram,
it's a little bit hard to detect
but it does appear to me that
those homes selling for less money have fewer bedrooms.
Those homes that sell for more money, more bedrooms.
Now let's do something interesting.
Let's add one more characteristic
to this scatter diagram, the number of baths.
I will drag baths to color and I will edit the color
to make it look more attractive.
Well this is pretty interesting.
The price of the home does seem
to depend upon size of the home
and more expensive homes certainly
seem to have more bathrooms.
This visualization tells this
kind of creative story about our data,
that by just looking at the raw data,
meaning the numbers, one might never detect.
This is the power of data visualizations.
Before I leave you, I want to show you one
interesting visualization that I came across that uses
some of what we have just learned.
I am a snow skier
and a little while ago I came across this
interesting graphic, I think it could have been
in the Economist, showing how much piste
do you get for your money?
It compares the average user rating
of various ski resorts to the cost of skiing there.
It also shows, in color,
where these ski resorts are located
and it uses size to represent
the total piste at each resort.
Basically the amount of skiable terrain
at each of these ski resorts.
I thought hm, this is pretty interesting.
Many of the European ski resorts
are also a bit expensive, but not all.
Vail, a mountain that I have skied,
comes up with a high user rating, which I would agree too,
but it also has a very expensive cost.
And interestingly, it doesn't offer more skiable terrain
than a good share of the European ski areas.
Keystone has a pretty good user rating.
It's maybe half the cost of skiing at Vail
and it does offer a fair amount of skiable terrain.
All of these characteristics I have experienced
by skiing Keystone.
So I found this graphic pretty interesting.
What I wondered was,
whether I could recreate this graphic using Tableau.
As you gain experience using Tableau
you will probably notice graphics
from various sources where you would sit back and say
the user created this using Tableau.
So I tried to recreate this graphic myself using Tableau.
I could not find the source of the data
but I was able to create some of my own.
Here's where I ended up.
I think that you will see that I am off
to a pretty good start recreating this visualization.
I hope that when you see interesting visualizations,
that you will attempt to recreate them on your own.
As with most software products,
the more you use Tableau, the better you get
at producing these visualizations.
I will share this ski resort visualization with you
on my resources web page.
I do not expect you to recreate it on your own.
Thanks for taking time to spend some moments with me.
I hope that you have enjoyed what I have shared with you.
If you ever have any questions or need my help,
please let me know.
(soft jazz)