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Week 9: Persistent Organic Pollutant Regulation
10-23-2014, 02:51 PM
Post: #1
Week 9: Persistent Organic Pollutant Regulation
[Image: epi-map-1024x562.jpg]

Discovered through: Scientific American

Direct Link to Article (scroll down for interactive map)

The visualization that I chose to critique is based on a dataset derived by researchers at Yale. I will begin by briefly summarizing the semantics of the data. The image displayed above is a still from an interactive map that allows users to discover how various nations have chosen to regulate Persistent Organic Pollutants (POPs), which include various pesticides, industrial chemicals, and by-products. Each nation was assigned a score based on the actions taken to limit the use of POPs. The exact metric for scoring is described on the article. A higher score indicates that most of the 'dirty dozen' POPs described by the Stockholm Convention are either banned or restricted by the nation and that the nation. A few additional points are earned if the country has signed and/or ratified the Stockholm Convention. The purpose of this visualization, as stated by the authors of the article, is "to help inform policymakers and other decisionmakers on pesticide usage".

With the first half of this course under our belt, we now have the necessary tools to describe this visualization using an abstract language unrelated to the problem's domain situation, i.e. environmental science. Clearly, the visualization is a map of the world, so the underlying dataset would be classified as spatial geometry. Each country could be considered an item with at least one attribute: the assigned score. I would argue that the score is a quantitative attribute since meaningful data could be derived by doing arithmetic using multiple countries' scores. Since the score has zero as its baseline and can only be incremented, it must be considered sequential. Hovering over a country reveals both which POPs the nation has reported it bans/regulates as well as whether the country signed/ratified the Stockholm Convention, so the status of each could also be considered a categorical attribute. Based on the metric described in the article, the score attribute is technically derived from these other attributes (it could also be considered an aggregation of the other attributes, since we could describe a function where the input is a set of attributes and the output is a kind of "similarity score").

Color was used to encode the score without needing to hover over it to see the actual value. However, I believe the color map used by the researchers was a poor choice: multiple hues were used to encode non-categorical data (i.e. the score), violating the expressiveness principle. The legend appears to diverge from the middle instead of strictly increasing from zero. Using saturation or luminance would have been a better choice. Hue was also used to encode the status of each attribute on the right side of the screen, but I think this choice was fine since the attributes within that pane are all categorical.

I like the fact that the creators of this visualization supported a basic interaction. Highlighting a country dynamically populates a linked view with the data associated with that country. In this manner, the map serves as an overview of the entire dataset by filtering out all attribute information except for the final score, whereas the linked view on the right only displays one item, but contains every attribute. Since the information appears as the user explores the map, I believe this could be considered a form of dynamic querying.

In terms of personal preference, there are some other things I might change or add. I think a scented interactive legend that could highlight countries within a certain range of scores would be a useful addition. I might also change how the scores for countries with no information on POP regulation are calculated. Currently, if a country hasn't reported information regarding a particular POP, the score is considered equal to allowing that POP. This can lead to misleading results, such as Russia (which has no information but the fact that they signed the Convention) having the same score as Mauritania (which explicitly allows all of the 'dirty dozen' POPs). Finally, it would potentially be useful to offer some alternative linked views to support other options for exploring the underlying data. For instance, a panel to highlight countries that match some sort of status. Then a user could easily find all countries that ban DDT but allow Dioxins and Furans, for instance.

Overall, I think this is a useful visualization that would already be suitable for its intended purpose of informing policymakers, especially for making quick comparisons without having to know much about the underlying data. It is intuitive to use and mostly obeys the principles we've studied. Some small improvements would make it even more informative without sacrificing usability.
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10-24-2014, 04:31 PM
Post: #2
RE: Week 9: Persistent Organic Pollutant Regulation
This is a good visualization to make a quick comparison without having to look at the underlying data. We can highlight a particular country to look at the data associated with the country. I also agree with Matthew on using the same color code for the country with no information about POP as the one with the country which allows POP. But it seems they did this for Russia but not for Afghanistan/Greenland (They have grayed out these countries). They should have at least made it consistent. Overall, it was a good graph, but few improvements here and there would have made it better.
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10-26-2014, 11:39 AM
Post: #3
RE: Week 9: Persistent Organic Pollutant Regulation
I liked the use of colors to encode the score that each country received based on the steps taken to control the use PoPs. This gives a lot of information at a quick glance. Then there is interactivity, by hovering over a country we can see additional details. This enables a user to get an overview as well an in-depth information from this visualization.
I do see some problems, some of the color hues are not easily distinguishable, moreover there is no support to view countries in a particular band only. Providing this feature could highlight countries who have not taken sufficient efforts to control PoPs.

Nonetheless, this is an interesting visualization which is providing the required information quickly and so it serves its purpose.
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10-26-2014, 01:26 PM
Post: #4
RE: Week 9: Persistent Organic Pollutant Regulation
I think Matthew Turner did a great job of summarizing what this visualization did right and what it did wrong. Hue was used where luminance would have been a better choice in the map view. The interactive features are very nice. Hovering over a nation gives a good high level summary of the data for that particular country.
I am not sure if I agree with assigning a score based on the set of POPs. Giving a score based on the set of POPs used seems to imply that there is an equal weight for all POPs, but in reality different POPs might be more or less harmful. I am not sure how you could create a visualization that would present some kind of information related to this. It would be nice to be able to view which countries use specific sets of pollutants. Trying to visualize the data might use to many channels though.
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10-26-2014, 09:51 PM
Post: #5
RE: Week 9: Persistent Organic Pollutant Regulation
The visualization is pretty intuitive. The interaction makes like easier for users. But I think adding filtering function could make the visualization even better.
- Image that the user click on the 'Banned' and then click on 'DDT' and 'PCBs', all those countries having DDT and PCBs banned could be shown with a pop-out color while others be dimmed out. This function will let user quickly filter out information there are not interested in.
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10-26-2014, 10:30 PM
Post: #6
RE: Week 9: Persistent Organic Pollutant Regulation
One particular thing I would change would be the colors used to describe the status of the chemicals in each country. Banned and No Info have similar colors used in the total country score color set, which can cause a bit of confusion. Also, comparing details in different countries could be difficult since you'd have to hover over each country one at a time. I agree that some highlighting would go a long way in showing chemical-specific trends.

Overall I think the visualization is good and fills its intended role.
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10-27-2014, 07:08 PM
Post: #7
RE: Week 9: Persistent Organic Pollutant Regulation
This is a great visualization and I like it. I agree with Mathew for the most part. I like the color used in the legend that is used to describe total score. It's very comfortable to me. In addition, the great part in this visualization is the interactive legend displayed on the right of the map. Viewers can easily obtain useful information, like rank, etc. Meanwhile, the author applied different color on each category indicating different information, like banned, restricted, allowed and no info. It is very straightforward to me. The author provides search function at right corner of the map that allows user check country easily. I would like to add a reset map function so that viewers could go back to the full map simply. Overall, this visualization is expressive and effective.
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