Day 7:
Today, we came across a new dimension of analysis. It was a
tool which gave us the power to visualize data in 3 dimensions and that was
bubble charts. A Bubble chart is a variation of a Scatter chart. A Bubble chart
can be used instead of a Scatter chart if your data has three data points. Bubble
charts can facilitate the understanding of social, economical, medical, and
other scientific relationships.
Usage
Use a
Bubble chart when you want specific values to be more visually represented in
your chart by different bubble sizes. Bubble charts are useful when your
worksheet has any of the following types of data:
- Three values per data point: Three
values are required for each bubble. These values can be in rows or
columns on the worksheet, but they must be in the following order: x
value, y value, and then size value.
- Negative values: Bubble
sizes can represent negative values, although negative bubbles do not
display in the chart by default. You can choose to display them by
formatting that data series. When they are displayed, bubbles with
negative values are colored white (which cannot be modified) and the size
is based on their absolute value. Even though the size of negative bubbles
is based on a positive value, their data labels will show the true
negative value.
- Multiple data series: Plotting multiple data series in a Bubble chart (multiple bubble series)
is similar to plotting multiple data series in a Scatter chart (multiple
scatter series). While Scatter charts use a single set of x values and
multiple sets of y values, Bubble charts use a single set of x values and
multiple sets of both y values and size values.
Formatting
Bubble charts:
There are
several ways to change the format of a Bubble chart:
- Display bubbles with a 3-D
visual effect: By selecting the 3-D Bubble chart sub-type, bubbles are formatted with a
3-D visual appearance.
·
Adjust the size of bubbles: The size of the bubbles can represent the area
of the bubbles or the width of the bubble, which affects the relative size of
one bubble to another. For example, you can use the Area of bubbles
option if you are charting rental costs of apartments for which you know the
specific square footage (such as 1,700 square feet). The Width of bubbles
option can be used for representations such as market share between products.
- Display error bars: To
graphically express potential error amounts relative to each bubble in a
bubble series, you can display error bars for the X values, the Y values,
or both.
- Change the color and fill
effects of bubbles:You can assign different colors and fill
effects (such as pattern, texture, and gradient) to individual bubbles or
an entire bubble series.
- Replace bubbles with pictures:You
can replace each bubble or all bubbles in a series with a picture. The
size of the picture is automatically adjusted to match the bubble size for
each corresponding value.
Source:
http://office.microsoft.com/en-us/excel-help/creating-a-bubble-chart-HA001117076.aspx
Various applications of bubble chart can be viewed through
following link:
Let’s look at the chronological flow of what we studied in
class today.
We started with Inter_cell file. Creating a similarity table
against the funuse attributes. Next we copy pasted the table in excel. This was
followed by selection of the date:
Insert-> Other charts-> Bubbles
Here we plot bubbles on the basis of x & y axis where as
the size of the bubble indicates the z axis. And that is how we form and take
use of bubble graph.
Then we went on to
get some more data from SPSS. Here we compared 4 stores on various satisfaction
parameters. Same process as before was carried out of copy pasting the table on
to excel and this time radars were used. Radar charts give us an indication of
the relative positioning of stores on various parameters.
Hence this completes the nuances of the sessions on BA for
today.
Submitted by:
Rahat Dhir
Team C
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