VizWiz

Data Viz Done Right

A-Rod's Projections

Scott Raab wrote a fantastic article in Esquire in February when the allegations came out about A-Rod taking steroids in 2003 (and who knows how long before or after). In the article, Scott references a chart published by Esquire in October 2008 that projects A-Rod's stats and when he's projected to pass significant milestones.

There are some fundamental flaws with this chart:
(1) The vertical axis starts around 400 instead of zero; this distorts the chart (In fact, when you start the axis at 0, runs scored and RBI are nearly identical. This chart makes it look like there is a variance worth noting.)
(2) The colored background is unnecessary and distracting; keep it transparent so that the data stands out on its own
(3) The markers at each point are not needed; they take away from the natural trend of the data
(4) The total should be labeled 2018, not total

There are also a few details that make the chart work:
(1) Identifying the major milestones
(2) Labeling the projected totals
(3) The color choice is good; the colors are discernible and no one color sticks out more than another (though the red could be slightly softer)

Given the notes above, here is how I would present the data:

Good news for A-Rod, his projected stats are even better than when Scott Boras presented the data for the first graph to the Texas Rangers back in 2001. Bad news for Boras, the \$252M contract you negotiated could have been higher if you presented your data more accurately (along with the 5% commission you lost).

Do oil prices have a direct correlation to the price of gold?

I recently read an article in Forbes about tracking oil prices. The theory is that oil prices have a direct correlation to the price of gold. Therefore most of the oil increase is a result of dollar inflation, not supply and demand.

What struck me immediately is the use of the scale to artificially highlight the correlation, a big no no in data visualization. Wanting to test the theory myself, I gathered the data and used Tableau to analyze it. As the article said, there is a strong positive correlation between the prices of gold and oil. Since the price of gold is typically ahead of the price of oil, I wonder if futures traders use this to set the price of oil or at least predict its direction.

As another interesting note, but not a surprising one, oil and gold prices can be correlated pretty strongly vs the consumer price index, which is a measure of inflation.

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Pie Chart Abuse

I ran across this post from the Replacement Level Yankees Weblog and it provided me with a fantastic example of a pie chart gone wild (aka chart junk).

Answer this question for me by looking at the pie chart: Which player had the 5th most RBIs?

Pie charts are designed to represent parts of a whole. Does this chart present the data this way? Well, I suppose it does, but is it done effectively? Certainly not. It appears the data is sorted in alphabetical order, but that doesn't provide any insight. If insisting on a pie chart, why not sort it descending by % of total RBI? Pie charts should be used sparingly, if ever. A simple bar graph displays the data much more effectively.

Answer this question for me again by looking at the bar chart below: Which player had the 5th most RBIs? Which chart made it easier to find the answer?