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title: Evaluating Cartogram Effectiveness
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# [Evaluating Cartogram Effectiveness](https://ieeexplore.ieee.org/document/7792176)

>[name=Presenter: Chun-Hung Yu][time=Date: Wed , Aug 11, 2020]
[name=Publisher: IEEE Transactions on Visualization and Computer Graphics][time=Published in: Feb 1, 2018, Volume: 24 , Issue: 2]

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* slide: https://hackmd.io/@king87515/ECE#

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## Abstract
- The large number of cartogram types, there are few studies evaluating the effectiveness of cartograms in conveying information.
- Four major types of cartograms
* contiguous cartograms
* non-contiguous cartograms
* rectangular cartograms
* Dorling cartograms (i.e circular)

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### Four major types of cartograms

| <font size=5>Contiguous</font> | <font size=5>Non-contiguous</font> | <font size=5>Rectangular</font>|<font size=5>Dorling</font>|
|:---|:---|:---|:---|
|  |  |  | |

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### Step
1. We first evaluate the effectiveness of these cartogram types by **quantitative performance analysis** (time and error).
- 7 visualization tasks in cartograms

3. We collect qualitative data with an attitude study and by **analyzing subjective preferences**.
4. We compare the **quantitative and qualitative** results with the results of a **metrics-based cartogram evaluation**.
5. We analyze the results of our study in the context of **cartography, geography, visual perception, and demography**.
6. We consider implications for design and possible improvements.

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## Cartogram Types
- 3 major design dimensions
* Statistical accuracy : 面積
* Geographical accuracy : 形狀
* Topological accuracy : 相鄰關係

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### Contiguous Cartograms (also called deformation cartograms) 
* <font size=6>**Deform** the regions of a map by pulling, pushing, and stretching the boundaries.</font>
* <font size=6>Allow for some cartographic error in order to better preserve **shape** and **topology**.</font>

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### Rectangular Cartograms 

* <font size=6>In rectangular cartograms there is often a tradeoff between achieving zero (or small) cartographic error and preserving the map properties (**relative position** of the regions, **adjacencies** between them)</font>

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### Non-contiguous Cartograms 
* <font size=6>They satisfy **area** and **shape** constraints, but do not preserve the topology of the original map.</font>

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### Dorling Cartograms 
* <font size=6>Data values are realized by size of the circle. However, in order to avoid overlaps, circles might need to be moved (typically as little as possible) away from their original geographic locations.</font>
* <font size=6>Unlike contiguous and noncontiguous cartograms, Dorling cartograms **preserve neither shape nor topology**. </font>

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## 7 Visualization Task In Cartograms
* Cartograms two type of information: **geographical** and **statistical**.
1. Compare
2. Detect Change
3. Locate
4. Recognize
5. Find Top-k
6. Find Adjacency
7. Summarize

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### 1. Compare
For similarities or differences between attributes.

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### 2. Detect Change
Whether a region has **grown or shrunk** is a central feature, it is crucial that the **viewer be able to detect** such change.

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### 3. Locate
Fnding the position of a region in the cartogram.

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### 4. Recognize
The viewer can recognize the shape of a region from the original map when looking at the cartogram.

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### 5. Find top-k
Find out the region with the highest or second highest value of an attribute.

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### 6. Find Adjacency
To identify the neighboring regions of a given region.

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### 7. Summarize
To convey the “big picture”.
Summarize tasks ask the viewer to find **patterns and trends** in the cartogram.

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## Attitude Study

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## Discussion
So, Which Cartogram is Best?

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## Design Implication
可以使用一些交互技術來彌補每種製圖的缺陷，像是滑鼠 hover 顯示資料資訊或者工具提示標籤等等...