Tools

Creating motion charts in Excel is a simple four-step process.

1. Get the data in a tabular format with the columns [date, item, x, y, size]
2. Make a “today” cell, and create a lookup table for “today”
3. Make a bubble chart with that lookup table
4. Add a scroll bar and a play button linked to the “today” cell

For the impatient, here’s a motion chart spreadsheet that you can tailor to your needs.
For the patient and the puzzled, here’s a quick introduction to bubble and motion charts.

What is a bubble chart?

A bubble chart is a way of capturing 3 dimensions. For example, the chart below could be the birth, literacy rate and population of countries (X-axis, Y-axis and size). Or the growth, margin and market cap of companies.

It lets you compare three dimensions at a glance. The size dimension is a different from the X and Y axes, though. It’s not easy to compare differences in size. And the eye tends to focus on the big objects. So usually, size is used highlight important things, and the X and Y axes used to measure the performance of these things.

If I were to summarise bubble charts in a sentence, it would be: bubble charts show the performance of important things (in two dimensions). (In contrast, Variwide charts show the same on one dimension.)

Say you’re a services firm. You want to track the productivity of your most expensive groups (“the important things”). Productivity is measured by 2 parameters: utilisation and margin. The bubble chart would then have the expense of each group as the size, and its utilisation and contribution as the X and Y axes.

What is a motion chart?

Motion charts are animated bubble charts. They track the performance of important things over time (in two dimensions). This is chart with 4 dimensions. But not all data with 4 dimensions can be plotted as a motion chart. One dimension has to be time, and another has to be linked to the importance of the item.

Motion charts were pioneered by Hans Rosling and his TED Talk shows you the true power of motion charts.

How do I create these charts?

Use the Motion Chart Gadget to display any of your data on a web page. Or use Google Spreadsheets if you need to see the chart on a spreadsheet: motion charts are built in.

If you or your viewer don’t have access to these, and you want to use Excel, here’s how.

1. Get the data in a tabular format

Get the data in the format below. You need the X, Y and size for each thing, for each date.

To make life (and lookups) easier, add a column called “Key” which concatenates the date and the things. Typing “=A2&B2” will concatenate cells A2 and B2. (Red cells use formulas.)

2. Make a “today” cell, and create a lookup table for “today”

Create a cell called “Offset” and type in 0 as its value. Add another cell called Today whose value is the start date (08/02/2009 in this case) plus the offset (0 in this case)

Now, if you change the offset from 0 to 1, “Today” changes to 09/02/2009. By changing just this one cell, we can create a table that holds the bubble chart details for that day, like below.

Check out my motion chart spreadsheet to see how these are constructed.

3. Make a bubble chart with that lookup table

This is a simple Insert – Chart. Go through the chart types and select bubble. Play around with the data selection until you get the X, Y and Size columns right.

4. Add a scroll bar and a play button linked to the “today” cell

Now for the magic. Add a scroll bar below the chart.
Excel 2007 users: Go to Developer – Insert and add a scroll bar.
Excel 2003 users: Go to View – Toolbars – Control Toolbox and add a scroll bar

Right click on the scroll bar, go to Format Control… and link the scroll bar to the “Offset” cell. Now, as you move the scroll bar, the value in the offset cell will change to reflect it. So the “today” cell will change too. So will the lookup table. And so will the chart.

Next, create a button called “Play” and edit its code.
Excel 2007 users: Right click the button, go to Developer – View Code.
Excel 2003 users: Right click the button and select View Code.

Type in the following code for the button’s click event:

Declare Sub Sleep Lib "kernel32" (ByVal dwMilliseconds As Long)
 
Sub Button1_Click()
    Dim i As Integer
    For i = 0 To 40:            ' Replace 40 with your range
        Range("J1").Value = i   ' Replace J1 with your offset cell
        Application.Calculate
        Sleep (100)
    Next
End Sub

Now clicking on the Play button will give you this glorious motion chart in Excel:

Watch Hans Rosling‘s TED Talks on debunking third world myths and new insights on poverty and ask yourself: could I do this with my own data?

Yes. Google has a gadget called MotionChart that lets you do this.

Now, you could put this up on your web page, but that’s not quite useful when presenting to a client. (It is shocking, but there are many practical problems getting an Internet connection at a client site. The room doesn’t have a connection. The cable isn’t long enough. You can’t access the LAN. Their proxy requires authentication. The connection is too slow. Whatever.)

So you need this in Excel. Let me explain a variant of the technique I described earlier.

Let’s start by creating a simple bubble chart.

For each item in a bubble chart, you need 3 pieces of data: the X-axis, Y-axis and size. This graph shows three items A, B and C in one year: 2001. To animate this, you need data for more years, so let’s create that.

The first 3 rows contain the same data as before, except that I’ve added a "Year" column and a "Key" column (which is just a concatenation of the Year and the Item). The data now goes on for many more years.

Now we need to create a scroll bar that can be used to change the year. So add a scroll bar below the bubble chart…

… and right click the scroll bar and go to Format Control. Now, select the cell link to some cell ($H$1 in this case). Now, if you move the scroll bar, the cell value will change.

All you need to do is to now change the source data for the chart based on the year. From the table on the left, VLOOKUP the year + item, and put this into the table on the right. When the year in the cell H1 changes, the data updates itself. So now, as you move the scroll bar, cell H1 changes, then so does the data and hence the graph.

This is what the animation looks like.

And here’s the Excel file.