Database Reference
In-Depth Information
In which other view can you tell, for example, that Manhattan produced
slightly
more refuse
than the Bronx, and that both yielded about twice as much as Staten Island? Not in the pie
chart (chart 7), where it's even difficult to discern which slice is the biggest. Refer again to
Figure 1-6
for a reminder of why this is the case.
But in which views can you speak to the
precise
amounts collected? If you needed to know,
for example, exactly how much more than 70,000 tons were collected in Brooklyn, which
would you use? Without adding data labels to the other views, the only ones that can help
with this task are the text table (chart 4), and the highlight table (chart 11).
When precision is required, tables work best, which is why finance departments make such
wide use of them. The highlight table adds some comparative value with the “color ramp”
encoding. At a glance, the color gradient gives a very general sense of which yielded the
most, and whether the amount collected was slightly more (Manhattan over the Bronx) or a
great deal more (Brooklyn over Staten Island).
The point here is that your choice of view type should depend largely on the message to be
communicated, which in turn depends on the task to be accomplished. Who are you commu-
nicating with, and how does the presentation of the data relate to the tasks at hand? These are
critical questions to answer.
Fine-Tuning the Default
If we decide to go with the recommended horizontal bar chart, we will get a view that is sor-
ted in alphabetical order, as shown in
Figure 3-4
.
Notice that Tableau has placed a green pill on the Columns shelf and a blue pill on the Rows
shelf. The Rows shelf contains the Dimension (or nominal field)
Borough
, and you can see
that there is a different row for each borough. The Columns shelf contains
SUM(RefuseTonsCollected)
, which indicates that Tableau has added the amounts in the
RefuseTonsCollected
field for all of the community districts in each borough, and is dis-
playing the total (we'll explore other measures such as averages and medians later).
Rather than using the Show Me drawer, you could have manually dragged both fields from
the Dimensions and Measures sections on the left side onto the Rows and Columns shelf, re-
spectively. Click the left Undo button and try it out.
