Storytelling with Charts. Half 4 (II): Do you wish to present… | by Darío Weitz | Jul, 2023

Half 4 (II): Do you wish to present Composition?

Photograph by Jonatan Pie on Unsplash

That is the second half (of a fourth article) whose goal is to point that are the very best knowledge visualization methods when the aim of the message to be delivered to the viewers is to point out the composition of the information.

It’s extremely beneficial, for a greater understanding of the contents of this text, to learn (or revisit) the previous article the place the idea of Composition and a few of its parts of study have been described.

In that earlier article, we indicated that the next have been six charts mostly used to point out composition: pie charts; stacked bar charts; Treemaps; stacked space charts; waterfall charts; Marimekko charts.

The primary three on the listing have been described intimately in that article. Now, we’ll think about the final three in that listing (Stacked Space Charts; Marimekko Charts; Waterfall Charts).

Allow us to first outline what an area chart is: it’s a sort of line chart with the world between the road that connects knowledge factors and the horizontal axis full of a specific shade.

There are 4 various kinds of space charts: 1) Commonplace Space Charts; 2) Stacked Space Charts; 3) % Stacked Space Charts; 4) Overlapping Space Charts. Solely Stacked Space Charts (StACs) and % Stacked Space Charts (%StACs) are used to point out Composition.

In each Stacked Space Charts, a number of areas are stacked on prime of each other. They show the evolution of a numerical variable over time (dynamic composition) with a 3rd variable, normally categorical, used to point out composition.

Associated to StAC, it’s a Half-to-Entire chart the place every space signifies the absolute worth of every half referred to the entire of the class. Associated to %StAC, additionally it is a Half-to-Entire chart the place every space signifies the share of every half referred to the entire of the class. There is no such thing as a overlapping between the totally different areas. In a StAC, the ultimate top of the vertical axis is expounded to the sum of all of the numerical values represented. In a %StAC, the ultimate top of the vertical axis is at all times 100%.

Determine 1 exhibits a StAC representing PS4 gross sales in 4 totally different areas between 2013 and 2018. The legends proven within the higher proper nook of the chart point out to which area the totally different coloured areas belong. It may be seen how every area (every space, every half) contributes to complete gross sales (the entire, sum of gross sales). The peak of every space represents absolutely the worth in gross sales of every specific area while the ultimate top is the sum of these values indicating complete gross sales per 12 months. It may be seen {that a} StAC needs to be used primarily to speak the general pattern and the relative contribution of every half to the entire with out caring about displaying actual numerical values for every half.

Fig. 1: a Stacked Space Chart. Graph made by the creator with Plotly Specific.

Determine 2 is a %StAC representing the identical PS4 gross sales knowledge. Every space represents the share of every area associated to complete international PS4 gross sales. As indicated above, the ultimate top is 100%. Undoubtedly, one of these chart permits a greater evaluation of the composition of worldwide gross sales than the one proven in Determine 1.

Fig. 2: a % Stacked Space Chart. Graph made by the creator with Plotly Specific.

A ultimate warning: StACs and %StACs are comparatively troublesome to learn and comprehend as they depend on the viewers’s capacity to decode numerical info by evaluating stacked areas. We encourage utilizing them solely to speak the worldwide pattern and the relative contribution of every Half to the Entire.

They’re a specific sort of variable width bar chart. Marimekko Charts (MCs) are much like 100% stacked bar charts however differ from them in that their rectangular bars can have totally different widths.

MCs are used to point out two numerical variables for every class current within the knowledge set. They’ve two axes: the vertical axis has a 100% numerical scale while the horizontal axis might be both categorical or numerical. Rectangular bars are organized in a vertical orientation with no area left between them. The complete width of the horizontal axis is occupied.

Determine 3 shows a Marimekko Chart. The chart exhibits annual revenues per model and area. The proportion vertical axis signifies percentages per area whereas the horizontal axis signifies annual revenues per model. We’re indicating in only one chart two numerical values for every class and every subcategory.

Fig. 3: a Marimekko chart. Created with Vizzlo with permission (#1).

As I previously stated: “The weather that characterize a Marimekko chart might be seen: an oblong space divided into smaller rectangles of various width; vertically stacked rectangles; a horizontal axis that occupies the whole width of the chart; a vertical axis with a share scale; complete revenues per model on the highest baseline; totally different bar widths that permit calculating the relative contributions of every model to the entire revenues”.

Marimekko Charts can be utilized as an alternative to 100% Stacked Bars however just for static evaluation (to point out composition at a second in time). They need to by no means be used to point out composition adjustments over time.

Identical warning as indicated with Stacked Space Charts: MCs are troublesome to interpret as a result of people will not be so good at calculating areas, notably with an rising variety of rectangles.

Waterfall Charts (WCs) are a specific sort of bar chart representing the cumulative results of information that swings between additions and subtractions. The message is to inform the story about composition adjustments between two knowledge factors.

A WC consists of an preliminary vertical bar, a set of intermediate vertical bars, and a ultimate vertical bar. The standard (and advisable) format is that the preliminary and ultimate vertical bars (columns) have the identical shade whereas the intermediate bars (floating bars) present a inexperienced worth for additions and a crimson worth for subtractions. It’s also customary for the primary and final columns to start out on the zero baseline.

Determine 4 exhibits a category-based waterfall chart with the traits indicated above. This kind of WC is habitually employed in human sources (displaying hiring and attrition in a specific division), in a specific enterprise (displaying revenues and bills), in a warehouse (inventory added, inventory taken), and in lots of different conditions the place knowledge swings between constructive and unfavorable values. Time-based WCs are used within the monetary trade (indicating positive aspects and losses all through a single time period).

Fig.4: a category-based waterfall chart made by the creator with Plotly.

A WC supplies extra contextual info than a regular bar chart. Whereas the latter solely exhibits the preliminary and ultimate values, the previous signifies the contribution of the weather of addition and subtraction to the entire and the composition of change between these preliminary and ultimate values.

This exceptional capacity to inform the story of the adjustments between the preliminary and the ultimate values has its counterpart within the complexity of appropriately decoding the magnitude of the adjustments. That is as a result of absence of a typical baseline within the floating columns which makes it troublesome to check the actual sizes of successive additions and subtractions. The most effective follow is so as to add numerical annotations within the columns and linking them with connecting horizontal strains (Fig.4 & Fig.5).

Determine 5 exhibits a time-based waterfall chart representing the story of adjustments within the variety of month-to-month guests to a fictional webpage. Some other visible illustration could be extra advanced for a median viewers to understand this specific scenario.

Fig.5: a time-based waterfall chart made by the creator with Plotly.

A vital query in any knowledge visualization mission is: “Did I select the proper chart to inform my story?”

The selection of probably the most acceptable chart will depend on the character of the message to be transmitted to our viewers.

Six various kinds of charts are used when Composition is the message to be transmitted: pie charts; stacked bar charts; Treemaps; stacked space charts; waterfall charts; Marimekko charts.

Our advice is to make use of pie charts for static composition and stacked bar charts for dynamic composition. Treemaps are a sound various when the Entire consists of ten or 1000’s of Components. Marimekko charts are acceptable for representing two numerical variables together with a principal class and its subcategories. Lastly, a waterfall chart solely exhibits the composition of change between preliminary and ultimate values.

For those who discover this text of curiosity, please learn any of my 56 earlier: Greater than 300 Ok views about Information Visualization, Simulation, Monte Carlo Approach, Dashboars, and so forth.


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