National Performance and Dominance

The visualizations below explore the performance of countries in the Summer and Winter Olympic Games from 1896 to 2016. The data is visualized using heatmaps, faceted bar charts, line chart matrices, and area density charts to analyze individual national performance and dominance of countries in different events over time. The visualizations are interactive and allow users to explore the data by selecting specific countries, years, and seasons. Following are the research questions supported by the visualizations:

• Which countries have been the most dominant in terms of total medals won?
• How has the performance of top-performing countries evolved over time?
• How does medal count distribution differ between Summer and Winter games for top-performing countries?
• Are there specific sports or events where certain countries have consistently excelled?

The first two views down below show the distribution of medals won by countries in the Summer and Winter Olympic Games from 1896 to 2016. The heatmap shows the number of medals won by all countries over the years, while the detailed linked chart connected to it allows for an interactive country exploration. The faceted bar chart in the second view shows the distribution of medals won by countries in a specific year for a specific season. All these charts in both views are bidirectionally linked to each other and allow users to explore the performance of countries in different seasons over time.

The third view of a line chart matrix below shows the performance of countries in different sports over time. The line chart matrix shows the number of medals won by countries in the top 12 most popular sports in a season. The line charts are interactive and allow users to explore the performance of countries in different sports by selecting specific countries, sports, and seasons.

The final view of the area density chart below allows users to explore individual countries (top 50) through time. With the customization of a time window using the bottom chart in this view, users can analyze the performance of a country over a specific period of time. The time window chart also has individual country dots overlaid on the total medal counts for the top 50 countries, so users can compare the trend of a country in comparison to the other countries.

Tasks Supported

The visualizations above support the following tasks by employing interactive heatmaps with linked detail brush charts, faceted bar charts, line chart matrices, and area density charts that dynamically adapt based on user selections:

• Analyze Country Trends: To identify the most dominant countries in terms of the number of medals won.
• Explore Time Trends: To visualize the domination of countries in different events over time.
• Compare Seasons: To compare the performance of top performing countries in different events over both Summer and Winter seasons.
• Explore a Country: To choose a country to analyze in more detail in terms of the number of medals won over the years in both Summer and Winter seasons.
• Analyze Performance in Popular Sports: To identify how different countries have performed in the most popular sports in both Summer and Winter seasons.

Visualization Design Justification

Heatmap and Detail Brush Chart (Bidirectional Link to Each Other and Faceted Bar Chart)

• Mark: The mark type used is a point to represent each country's performance in a specific year in the heatmap (mark_rect). In the brush chart, the mark type used is a segment (mark_bar) to represent the medal counts won by a country in a specific year.


• Channels: For the heatmap, the horizontal position and order channel denotes years starting from 1896 to 2016, while the vertical position channel represents a country (NOC). The saturation channel represents the number of medals won by the country in each year and this is a magnitude ordered channel as the number of medals is a numerical attribute. Each cell in the heatmap has shared boundaries in terms of years and countries, horizontally and vertically respectively.
  For the brush chart, the horizontal position and order channels represent the year and the vertical position and order channels represent the number of medals won by a country. The color hue channel represents the type of season (Summer or Winter).


• Characteristics of Channels: In the heatmap, the sequential color scheme is used to encode magnitude of the number of medals won by a country in each year, helping users identify regions of high or low medal counts at a glance. The color scheme is appropriate as the number of medals is a numerical attribute and increases from a minimum to a maximum. The position channel for years helps the users read the graph from left to right with the years increasing from 1896 to 2016. The saturation channel and position channel are magnitude-ordered channels and adhere to the principle of expressiveness.
  In the brush chart, the 2 color hues (orange and blue) on the opposite ends of the color hue channel help the users identify the Summer and Winter seasons clearly without getting mixed up. The years are ordered from left to right in an increasing order enabling left to right reading and the number of medals are ordered from top to bottom in an increasing order enabling top to bottom reading.
  These channels are ranked highly in the list of magnitude and identity channels so we are following the principle of effectiveness.


• Interactivity: The heatmap is bidirectionally linked to the detailed brush chart in the same view and it is also bidirectionally linked to the faceted bar chart in a different view below it. Clicking on a cell in the heatmap will highlight the corresponding country in the heatmap and the corresponding country in the detailed brush chart view along with the corresponding country in the faceted bar chart. Similarly, clicking on a bar in the brush chart will highlight the corresponding country in the heatmap and the faceted bar chart. When you select a cell in the heatmap or a bar in the brush chart, everything else in both the charts will be unhighlighted, and clicking anywhere other than the highlighted parts will remove the highlight. This selection is preserved when you switch between seasons. Users can select a season to display the trends for Summer or Winter in both the charts using radio buttons. Users can also decide if they want to filter out countries based on how many medals they have won (low, medium, high) using a dropdown. The heatmap has a brush selection built in so rectangular regions can be selected and by moving this selection box around with clicking and dragging, you can view updates in the detailed brush chart. For both the heatmap and brush chart, there is a tooltip on hovering over a cell to show the number of medals won by the country in the selected season for the corresponding year.


• Critique: There is a lot of information being displayed in the heatmap, so users may not be able to completely understand the data at a glance. The heatmap is useful for identifying groups or clsuters of similar performance, but users may also not be able to compare the performance of different countries in different seasons as the heatmap only shows the performance of a country in a specific season and you have to use the radio buttons to switch between seasons, so you might have to manually remember the trends of the previous season. Due to the sequential color scheme, users might not be able to identify the magnitude of the number of medals won by a country in each year without hovering over cells. In the brush chart, it is hard to select a country as multiple countries are stacked on top of each other in the same bar and can face difficulty in distinguishing between similarly colored cells. There is a lot of interactivity in the charts (tridirectional links), so users might get overwhelmed with the number of options to choose from and might not know where to start exploring the data.

Faceted Bar Chart (Bidirectional Link to Heatmap and Brush Chart View)

• Mark: The mark type used is a segment (mark_bar) to represent the medal counts won by a country in a specific year.


• Channels: The horizontal position and order channel denotes medal counts starting from the minimum to the maximum, while the vertical position channel represents a country (NOC). The 1D length of the bars represents the number of medals won by the country in a specific year. The bar chart has been faceted by country so that each country has its own bar and each bar is aligned to the bottom of the chart for comparison with a common scale.


• Characteristics of Channels: The position channel on a common scale follows Weber's Law which states that human beings are more likely to compare objects on a common scale than on unaligned scales. It is easy to compare between 2 countries because the length of the bars is proportional to the number of medals won by a country in a specific year. The vertical position channel on a common scale is also easy to compare between 2 countries because the bars are aligned to the bottom of the chart. The 1D length of the bars is a magnitude ordered channel and adheres to the principle of expressiveness. The medal counts are encoded on the horizontal position channel as a magnitude ordered channel and adheres to the principle of expressiveness. All these channels are ranked highly in the list of magnitude channels so we are following the principle of effectiveness.


• Interactivity: This view is bidirectionally linked to the heatmap view and brush chart view. Clicking on any country in the chart will also show the country trends in the heatmap and brush charts. There is a year dropdown menu to select a specific year to display the medal counts won by all country in that year and when you select a year, the heatmap will display that year with a vertical red line. You can also select a season to display the medal counts for Summer or Winter using radio buttons. Faceting by country ensures clarity when exploring multiple data points. Lastly, there is a tooltip on hovering over a bar to show the number of medals won by the country in the selected season for the corresponding year.


• Critique: For some seasons in certain years, not all countries take part in the Games, so users might see fewer or more countries on choosing different years or seasons. The dropdown menu for selecting a specific year can be long to scroll through and can get overwhelming pretty quickly if you are not familiar with the data. Not all countries can be shown in the chart due to information density issues, so users have to settle for a smaller number of countries (top performing ones).

Line Chart Matrix

• Mark: The mark type used is a line (mark_line) to represent a country over multiple years.


• Channels: The horizontal position and order channel denotes years starting from 1896 to 2016, while the vertical position and order channel represents medal counts and these are both numerical attributes represented by magnitude-ordered channels. The color hue channel which is a identity channel for categorical attributes represents a country (NOC).


• Characteristics of Channels: The years are ordered from left to right in an increasing order enabling left to right reading and the medal counts are ordered from top to bottom in an increasing order enabling top to bottom reading. With the categorical-identity color hue channel, users can easily choose a country and follow its trend over multiple years as country is a nominal attribute. These channels are ranked highly in the list of magnitude and identity channels so we are following the principles of effectiveness and expressiveness. The line chart matrix is column-faceted by sports so that users don't have to scroll through a long list of sports to find the one they are interested in and these faceted charts share a common axis for effective comparison.


• Interactivity: By default, the line chart shows the medal counts won by 5 countries in all years in certain sports. You can use the "Number of Countries" slider to choose the number of countries to display at any given time on all the charts (default value is 5). The sports shown are the top 12 most popular ones in a season and they are column-faceted. With the "Select Sport" dropdown, you can either choose a specific sport to display on the entire map or select "All Sports" for the default view. You can select a season to display the medal counts for Summer or Winter using radio buttons. You can also click on a line in the chart to only show that country in all the line charts (other country lines are dimmed) and this selection is preserved when you switch between seasons. Clicking anywhere else in the chart will remove the highlighted country selection. Lastly, there is a tooltip on hovering over a line to show the number of medals won by a country in the selected season for the corresponding year for that sport.


• Critique: When the chart is showing all the countries in a season, it is hard to compare the performance of different countries in different sports because the lines cross each other multiple times over the years and there is a bit of cluttering for low values of medal counts. Due to this clutter, it can be difficult to click on an individual line to view its details and there can be frequent misclicks. It can also be difficult to get the exact medal count for a country without hovering over its line as the vertical axis is only for the charts on the left margin.

Area Density Chart

• Mark: The mark type used is an interlocking area (mark_area) to represent the medal counts won by a country in a specific year. The bottom chart uses a mark type of point to represent an individual country.


• Channels: The horizontal position and order channel denotes years starting from 1896 to 2016, while the vertical position and order channel represents medal counts and these are both numerical attributes represented by magnitude-ordered channels. The color hue channel which is a identity channel for categorical attributes represents a country (NOC).


• Characteristics of Channels: The years are ordered from left to right in an increasing order enabling left to right reading and the medal counts are ordered from top to bottom in an increasing order enabling top to bottom reading. With the categorical-identity color hue channel for the 2 charts, it is easy to distinguish between which chart represents all countries and which one represents individual country trends. These channels are ranked highly in the list of magnitude and identity channels so we are following the principles of effectiveness and expressiveness.


• Interactivity: The first thing a user has to decide is which country they want to see the trends for. You can use the "Country" dropdown to choose a specific country to display. Once you have chosen a country, by default, the top chart shows the medal counts won by that country in all years in both seasons. The bottom chart (Total Medal Counts for Top 50 Countries) has a brush selection built in so rectangular regions that represent the time window you want to analyze can be selected and by moving this selection box around with the mouse, you can view updates only for that time window in the top chart. Whenever you select a country in the dropdown, the bottom chart will show the medal counts for that country in all years using red points, so you can compare the trend of that country in comparison to the total medals won by the top 50 countries. Lastly, both charts have tooltips that have information about the number of medals won by a country in a specific year.


• Critique: The country selection dropdown has 50 options so it can be a bit long to scroll through and can get overwhelming pretty quickly if you are not familiar with NOC codes. The area density chart is useful to identify general patterns in the data, but it can be hard to identify small and subtle differences in medal counts between years.