Clicking the triangle next to a Value field brings up visualization options, such as changing Sum to Average.
(If the graph is too small, just click and drag a corner of the box to resize it.)
The graph is currently sorted by airline alphabetically. If you want it sorted from highest to lowest, click the ellipsis at the top right and choose Sort By > Average of DEP_DELAY.
Clicking the ellipsis at the top right of a graph brings up sorting options.
Arrival delays would be interesting, too. Drag ARR_DELAY onto the Value area of the panel and change it from Sum to Average. Click the ellipsis again at top right to sort by ARR_DELAY descending (if it defaults to ascending, just click again). You should now have a graph that looks like this:
A graph showing departure and arrival delays.
(You can see a version of your graph that takes up the whole canvas by clicking on the "Focus mode" icon next to the ellipsis at the top right of the graph's borders.)
The default title is a little lame. You can change the title and a lot of design defaults by clicking the brush icon just below the Visualizations options. To edit a specific graph, make sure you click it so it's active (the bounding box is visible). Click on Title and you'll see options to change the title text, font color, size, alignment and so on.
There are also options to add data labels to the bars, change the X- and Y-axes, and more.
For example, you can change the title to Average Departure & Arrival Delays in Minutes, Jun - Sep 2015, bump up the text size and center-align. If you want to rename fields, you can do that on the Fields panel -- right-click a field and choose rename. Try changing DEP_DELAY to Dep Delay and ARR_DELAY to Arr Delay.
Well, it sure looks like Spirit Airlines wasn't the best choice last summer -- but maybe the airline has big delays in some airports but not others? We can revise the visualization to include just a few airports.
There are a couple of ways to narrow in on a subset of data. Filters can apply to one graph, the entire page or all pages in a multi-page report. You can change filters while editing a report; but if you subsequently share your work as a Power BI dashboard, read-only users will see only what you filtered and won't be able to add data back in.
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