Bar Charts versus Pie Charts

In a presentation, the purpose of a chart or graph is to make one point, vividly. Tell a story and move on. If you can’t be both vivid and truthful, it doesn’t belong in your presentation.

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A Bar graph is a chart that uses either horizontal or vertical bars to show comparisons among categories. One axis of the chart shows the specific categories being compared, and the other axis represents a discrete value. Some bar graphs present bars clustered in groups of more than one (grouped bar graphs), and others show the bars divided into subparts to show cumulative effect.

A Pie Chart is a circular graph used to show the relationship of a part to the whole, using sectors that are parts of the circle graph and are proportional to the other data displayed. Values are represented by percentages with each chart representing 100%.

Bar charts and pie charts can help your audience understand your ideas, results, and conclusions quickly and clearly.

Both pie charts and bar graphs are designed to help you communicate your survey results, but to convey your findings as clearly and accurately as possible you need to choose your graphs carefully.

When to Use Bar Graphs and Pie Charts

The general rule of thumb here is that bar charts are the most commonly used types of graphs, and should be your go-to choice for most data visualization.

Bar graphs are very flexible since there are four different kinds, each of which can reveal different types of trends or relationships that you can’t show as easily with pie charts. There are simple horizontal or vertical bar-charts, with groups in clusters (where you can also add colored bars), bar-charts with stacked groups or  bar-charts with groups on separate panels. Somehow pie charts became standard when tools like word processing and spreadsheet software started creating them for us, but there are few times when they tell a better story than a bar graph.

Here are a few cases when pie charts work best:

1. When you have only a few data points to display, and each one is substantially different in scale.

2. To show that a few key data points represent the vast majority of the whole.

3. To start a discussion about a general trend rather than convey precisely accurate data.

4. To compare similar responses across different time periods, age groups, genders, etc.

Pie charts have recently come under fire from data visualization experts who argue that they are relevant only in the rarest of circumstances. Bar graphs, charts, and tables, they say, are far superior ways to quickly get a message across.

To compare different data samples or to show how individual elements contribute to an aggregate amount, use bar charts. A bar chart represents each element of a data sample as one bar. Bars are distributed along the horizontal or vertical axis, with each data element at a different location. To compare data samples, create a bar chart for two or more data samples.

Pie charts can help you effectively communicate a portion (or percentage) that each element of a data sample contributes to the total number of all elements.

In some cases Pie Charts are not recommended for data visualization and can be advantageously replaced by simple bar charts:

  • Pie Charts does not work well with more than 5 categories
  • It is difficult to compare areas (here slices)
  • Sort is not immediately visible
  • Small values cannot be read easily
  • A legend is frequently needed
  • Colors are needed just to distinguish slices

Pie charts are still frequently used mainly because this is how percentages are taught at school and also because a pie chart immediately conveys the idea of percentage. But that does not counterbalance all the weaknesses of this chart.

Pie charts are not without their strengths. The primary strength of a pie chart is the fact that the message “part-to-whole relationship” is built right into it in an obvious way. Children learn fractions by looking at pies sliced in various ways and decoding the ratio (quarter, half, three quarters, etc.) of each slice. A bar graph doesn’t have this obvious purpose built into its design.

Despite the obvious nature of a pie charts message, bar graphs provide a much better means to compare the magnitudes of each part. Pie charts only make it easy to judge the magnitude of a slice when it is close to 0%, 25%, 50%, 75%, or 100%. Any percentages other than these are difficult to discern in a pie chart, but can be accurately discerned in a bar graph, thanks to the quantitative scale.

Graphs are useful when a picture of the data makes meaningful relationships visible (patterns, trends, and exceptions) that could not be easily discerned from a table of the same data.

Look at the pie chart below and try to place the slices in order from largest to smallest. Cabernet Sauvignon Sangiovese Prosecco Chardonnay Syrah Tempranillo Pinot Grigio. Having trouble? As you can see, comparing the angles of the slices doesn’t make it any easier.

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Look at how easy it is to compare the percentages using the bar graph below, which displays the same values:

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The pie chart, like all graphs that use the position, length, or area of objects to represent quantity, includes an axis with a quantitative scale, only it is never shown. The axis and scale of a pie chart is not linear, as it is with most graphs, but circular, for it is located along the circumference of the circle. Here’s what a pie chart would look like if its axis and scale were visible:

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People love dressing up their pie charts today to look mouthwatering. Why stick with a simple 2-D pie chart when you can add a third dimension of depth to the picture and throw in some lighting effects and contoured edges while you’re at it, as shown here?

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It’s pretty and eye-catching, but is it more meaningful or easier to interpret? Actually, by adding depth to the pie and changing its angle, we’ve made it more difficult to interpret. The green slice now appears greater than it actually is, because of the depth that’s been added. The slices are now more difficult to compare, because the angle skews their appearance.

Try to follow the changes of these various companies and how they compare to one another through time. It is nearly impossible. Notice how easily you can do it, however, using the bar chart.

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Conclusions:

Hickey calls pie charts, “easily the worst way to convey information ever developed in the history of data visualization,” which may be taking things a little too far, but this example makes it clear that they’re not always the right choice.

If you don’t have dramatic differences in your data percentages, it can be hard to see distribution on a pie chart.

Regardless, the fact remains that a comparison of two sets of summed parts is rare in the real world. But, by all means, should you ever need to display data for this purpose, a pie chart would serve you well. Otherwise, save the pies for dessert.

Sources:

http://www.perceptualedge.com/articles/visual_business_intelligence/save_the_pies_for_dessert.pdf

https://www.surveygizmo.com/survey-blog/pie-chart-or-bar-graph/

http://chandoo.org/wp/2009/02/20/better-pie-charts/

Folosirea graficelor în dashboard

Cel mai bun mod de a afişa date va depinde întotdeauna de tipul de informaţii, natură mesajului, nevoile şi preferinţele privitorului. Un dashboard afişează, de obicei, multe informaţii şi necesită diverse artefacte pentru a le afişa.

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Acolo unde sunt multe informaţii , textul (în special cel structurat în tabel) este de preferat graficelor. Dacă foloseşti grafice căutarea unor date/valori exacte este mai dificilă. Pe de altă parte, dacă vrei să obţii o imagine de ansamblu, sau pentru a compara mai multe măsuri, textul nu mai este suficient, este nevoie şi de grafice.

În cadrul unui dasboard se pot folosi următoarele elemente:

1. Grafice:

1.1. Tables

1.2. Line charts

1.3. Bar charts

1.4. Pie charts

1.5. Scatter plots

1.6. Sparklines

1.7. Speedometers şi bullet graphs

2. Gauges: pentru a arată măsuri simple şi pentru a le compara cu valori predefinite

3. Icons: pentru a indica alerte, sus/jos, sau închis/deschis.

4. Text: etichete şi numere.

5. Organizers: tabele, hărţi.

6. Images: poze, ilustraţii, diagrame.

7. Drawings: care pot arată ierarhia sau fluxul.

Dacă spaţiul permite, indicat ar fi să se pună etichete în interiorul graficelor, aproape de informaţii, că privitorul să nu fie nevoit să se deplaseze înainte şi înapoi între grafic şi legendă. Dacă nu este posibil, o altă soluţie ar fi să se pună legenda aproape, sub grafic.

Foloseşte culorile altfel: joacă-te la saturaţia acestora pentru a diferenţia elementele.

Foloseşte pe lângă culori de asemenea şi simbolurile pentru a separa zonele.

Menţine un stil unitar, este de preferat să foloseşti acelaşi font de la un grafic la altul.

Textul ce compune eticheta graficului de asemenea ar fi bine să fie dispus pe orizontală, cel dispus pe verticală este mai greu de citit.

Sunt de evitat culorile prea stridente sau modelele încărcate.

Tables

Textul structurat pe rânduri şi coloane va fi mereu mai uşor de parcurs. Sunt cel mai des folosite pentru a furniza informaţii mai detaliate, facilitează compararea şi analiza datelor dar nu sunt potrivite pentru o imagine de ansamblu asupra acestora.

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Vertical bar charts

Sunt folosite atunci când privitorul trebuie să compare anumite valori. Poate de asemenea să pună în valoare tendinţe de-a lungul timpului.

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Horizontal bar charts

Se folosesc tot pentru a compara valori, etichetele acestora sunt mai uşor de citit.

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Diagramele verticale sau orizontale sunt folosite cel mai des pentru a arăta frecvenţe, sume şi medii. Afişând valorile individual putem face mult mai uşor o comparaţie între acestea.

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Pie Charts

Se folosesc pentru a arată distribuţia proporţională, procentuală.

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Linear Graphs

Este folosit pentru a vedea valori şi tendinţe de-a lungul timpului sau pentru a determina relaţia dintre variabile.

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Scatter plots

Arată relaţia dintre variabile, amploarea, direcţia, formă, şi viteză de schimbare pentru valori în timp, însă când sunt prea multe informaţii este bine sa le evităm pentru că devin aglomerate, punctele se suprapun şi sunt greu de citit.

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Sparklines

Cel mai simplu şi restrâns grafic, este folost pentru a compara tendinţele a mai multor elemente, pentru o vedere de ansamblu a acestora.

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Speedometers şi bullet graphs

Speedometrele nu sunt foarte des folosite, atâta timp cât dasboard-urile în general nu afişează date în timp real nu-şi au rostul.

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Graficul “bullet” pe de altă parte, este o alternativă mai bună la vitezometru, este mai compact, valorile sunt indicate clar, se poate face comparaţia între elemente foarte uşor.

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Concluzii

Este uşor să faci un dasboard slab din punct de vedere al designului, să aglomerezi multe informaţii, nu neapărat folositoare şi să le dispui prost. Dasboardul trebuie să fie conceput în aşa fel, folosindu-se grafice, ierarhizări şi prioritizari de informaţii încât să-i fie uşor utilizatorului să-l descifreze.

Surse:

http://ux-guidelines.visma.com/printItem?document=c0ac3c37-cfee-4ea1-8452-a6da50834fb0&itemUUID=bd1cfb22-4d37-44df-828b-58653e592861

http://www.uxmatters.com/mt/archives/2010/11/dashboard-design-101.php

Dasboard-ul

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Dashboard-urile trebuie să comunice informaţiile importante dintr-o privire. Dacă un dashboard nu reuşeşte să-ţi transmită imediat ceea ce vrei să afli, nu-l vei mai folosi niciodată, chiar dacă este plin de elemente frumoase.

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Dashboard-ul ar trebui:

  • Să ofere o imagine de ansamblu.
  • Să evidențieze ceea ce are nevoie de atenție.
  • Să furnizeze metode uşoare de a intra în detalii acolo unde este necesar.

Dashboard-Sketch

Un dashbord bine-conceput te ajută să înţelegi informaţiile, însă, prost conceput, poate aduce mai multă confuzie în loc să ajute. În cazul în care nu vei vedea informaţii relevante la momentul potrivit, poţi pierde din vedere obiectivul şi este posibil să porneşti în direcţia greşită.

Iată 6 sfaturi pentru crearea unui dashboard:

1. Identifică obiectivul

Identificaţi un obiectiv pe care încerci să-l realizezi şi construieşte dashboard-ul în jurul acestuia. Stabilirea obiectivelor te ajută să te concentrezi pe detaliile importante care urmează să fie afişate şi în acelaşi timp exclude informaţiile irelevante.

2. Defineşte publicul

Utilizatorii vor caută tipuri diferite de informaţii. De exemplu, directorii sunt, în general interesaţi de informaţii generale, cum ar fi numărul de utilizatori înscrişi lunar, utilizatorii activi în ultimile luni. Alţi membrii, cum ar fi managerii de produs, managerii de marketing, etc vor dori să monitorizeze performanţă de zi cu zi şi cazurile particulare, excepţiile. Cele mai eficiente dashboar-uri afişează informaţii din aceiaşi categorie.

3. Dispunerea componentelor

Că o strategie de design, plasaţi informaţiile cele mai importante în regiunea stânga-sus a dashboard-ului. Cele mai puţin importante sau cele care se schimbă rar ar trebui să fie plasate în partea de jos a paginii.

4. Gruparea elementelor

Gruparea informaţiilor înrudite permite utilizatorilor să descopere şi să înţeleagă legăturile dintre ele. Să plasezi informaţii înrudite la mare depărtare unele de altele poate induce în eroare utilizatorul, îl pot face să vadă mai greu imaginea de ansamblu.

5. Foloseşte strategic culorile

Culorile pot fi utilizate pentru a evidenţia informaţii importante şi pentru a arată relaţiile dintre elemente. Pot fi un real ajutor pentru utilizator în a obţine mai uşor perspectiva asupra informaţiilor.

Adesea o imagine face cât o mie de cuvinte, foloseşte imagini şi simboluri în dashboard-ul tău.

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Concluzii

Dasboard-urile desktop vor furniza informaţii şi analize detaliate, dashbord-urile pentru mobil vor fi destinate să răspundă cerinţei utilizatorului de informare rapidă şi concisă.

Poate fi destul de greu să realizezi un dashboard eficient, dar potenţialele beneficiile fac să merite încercarea. Cheia stă în aplicarea conceptelor simple.

Surse:

https://uxmag.com/articles/the-psychology-behind-information-dashboards

https://uxmag.com/articles/four-cognitive-design-guidelines-for-effective-information-dashboards

http://ux.walkme.com/design-effective-information-dashboards-business/

Design Effective Information Dashboards for your Business

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An Information Dashboard is a real-time display of the key performance indicators of your business. It tells you how your business is doing, which business areas are performing well and which ones need to be improved.

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“A single-screen display of the most important information needed to do a job, designed for rapid monitoring.” (Stephen Few)

The mission of a dashboard should be to:

  • Provide an overview of what’s going on.
  • Highlight what needs attention.
  • Provide easily discoverable ways to drill down into details as necessary.

A dashboard is often designed as the initial view when logging into a system.

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Well-designed dashboards make it easy to understand critical information and gain insights. If not designed properly, they can hurt your business instead of helping it. For example, your CEO won’t be able to spot risks immediately, and critical areas that need urgent attention may get ignored. If your team doesn’t view relevant information at the right time, it may lose focus and move in the wrong direction.

Here are 6 tips you can use to design effective information dashboards for your business.

    1. Identify the objective

Identify a single business objective you are trying to accomplish, and design a dashboard around it. Setting objectives helps you focus on the key metrics to be displayed and exclude the irrelevant ones.

2. Determine the audience

You need to ask yourself, “Who will see this dashboard and what will they look for?” Operations team, Product Managers, Executives, etc.?

Different team members look for different kinds of information. For example, Executives are generally interested in high-level performance such as total signups or monthly active users over past few months. More tactical members like Product Managers, Marketing Managers, etc. want to monitor day-to-day performance and spot deviations from the norm. The most effective dashboards display information relevant to a single type of user.

3. Layout the components logically

We know from UX studies that when we see a web page, our eyes generally start at the top-left region of the page. As we read the contents, our eyes move from left to right. Well-designed dashboards take advantage of this natural reading pattern.

As a dashboard design strategy, place the most urgent and important information at the top-left region of the dashboard. Low-priority and infrequently-changing information should be placed towards the bottom region of the dashboard.

4. Group related components

Grouping related information enables users to discover and understand connections between them. On the other hand, placing related elements far apart can confuse the user and make it harder to see the big picture.

5. Use colors strategically

Dashboards are often packed with a lot of information and can be, sometimes, overwhelming. Colors can be used to highlight key information and to show information relationships. This helps users gain insights easily.

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To perform any kind of analysis using a dashboard, the user must be able to extract and process visual stimuli reliably and quickly. The interface should be such that it guides visual processing and doesn’t deter it.

Also, prioritization of information helps make the dashboard more readable. As Amanda Cox, Head of The New York Times Graphic Department once noted, “Data isn’t like your kids. You don’t have to pretend to love them equally.” Know where to focus your user’s attention.

Information dashboards give users the control over our environments that we crave on a psychological level.

With its interactive and intuitive interface and its ability to visualize data in a single screen, it’s becoming a critical tool in the hands of the business user.

So what makes information dashboards so appealing to the human mind? What is it that the human mind seeks that is so nicely provided by information dashboards?

Desire to Control, we love to be in control.

An information dashboard gives you that control. Whether it’s a personal finance dashboard that makes you conscious of you spending trends or an enterprise marketing dashboard that helps you keep track of your marketing budgets, both heighten your awareness of a situation, giving you the sense of control you crave.

Most information dashboards use a three-pronged strategy to establish a sense of control:

  • Giving you a clear understanding of things to help establish a feeling of certainty.
  • Giving you the resources to predict and plan for the future.
  • Helping you complete critical tasks in time to avoid last-minute panic.

Dashboards work by overcoming this limitation of short-term memory. By displaying all relevant information on a single screen within a user’s eye span, they reduce the dependence on the short term memory. You don’t have to remember anything because it’s all there in front of your eyes.

Any product that has an information dashboard as one of its key offerings should keep the psychological needs of its end users in mind. Users like being in control, they have a limited short-term memory, and they love things that are simple. These three factors should form the foundation of all dashboard designs. Understand your user’s requirements and add in your design best practices and you have the ingredients for creating a good information dashboard.

We are wired for visualization. Whether it’s graphs putting raw data into a perspective or the use of icons, which helps to overcome issues of limited real estate, we do value a picture over a thousand words.

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Gestalt psychology offers a set of laws that explain how we perceive or intuit patterns and conclusions from the things we see. Applying these laws to charting and data visualization can help users easily identify patterns in their data.

Final thoughts 

Information-on-the-move will be a key feature of the information dashboard. While web dashboards will provide users with in-depth insights and analysis, the mobile dashboard will be tailor-made to suit the information requirements of the user-on-the-go. Location intelligence, real-time data and predictive analytics will further make the dashboard richer and enable users to gain crucial business insights from their data.

Information dashboards aim to augment human cognitive abilities and aid in decision-making. The challenges of designing an effective dashboard are many, but the potential benefits make this a challenge worth pursuing. The key is not in finding what’s most exciting or what’s most outside-the-box but in applying simple concepts which we know but still tend to overlook.

Sources:

https://uxmag.com/articles/the-psychology-behind-information-dashboards

https://uxmag.com/articles/four-cognitive-design-guidelines-for-effective-information-dashboards

http://ux.walkme.com/design-effective-information-dashboards-business/