Information hierarchy

I just returned from a short trip to Paris to show my son around some of the famous sites and restaurants. In 2021, that means a lot of health checks and tests. I was probably the only one in the airline terminal that looked at all the forms with the eye of a typographer.

I am not talking about elegance here, pure functionality. The people at check in desks are looking for “positive” or “negative”, the date the test was given, and whether the passport numbers match. On the test result form, the thing that is printed biggest is the name of the testing laboratory…

All this can be fixed easily with an adjustment of font sizes.

Rounding numbers in data charts

How to round numbers in a data chart? It depends. The chart below does not look very appealing

The numbers are hard to read. This chart can serve 2 purposes. Either show the trend in sales, or show the exact sales figures. To show a trend in sales, simply show the accounts in thousands, and round up to one decimal point:

If you need to provide the actual precise sales data (for accounting or tax purposes), put it in an appendix slide that does not even pretend to show a trend:

Scaling of data charts in SlideMagic

In SlideMagic, you do not have to worry about picking the right scale for your data chart. The entire chart adjusts itself to the numbers you type in. See the example below:

To make sure that a consistent scale is used for your entire chart, you need to place all your data points in one shape, instead of using multiple shapes for example for each month.

P.S. I have added this monthly sales comparison chart to the SlideMagic slide library so you can easily use it in your own presentations as well. Search in the app for ‘sales’ and it will pop up.

Leaving the math to your audience

It is raining COVID statistics in Israel as we are the first country in the world to deal with a post-vaccination outbreak. Below is one table that was released by the Ministry of Health (I found it here).

I have translated it in a quick SlideMagic chart (it always puts a big smile on my face to see how quickly this can be done).

But this data is horrendous to understand. Percent of what? What is 100%? The audience is left to do the math themselves. Compare the categories to the breakdown of the population, look at differences between 3 and 7 days ago, look at the ratio between mild to severe, etc. etc.

Using bars instead of numbers (another smile) makes things a bit clearer.

But in this case, it would have been clearer to release the data in absolute numbers and let people construct their own charts.

I have added the charts above to the SlideMagic library, search for COVID in the app and the slides will show up (see the search here).

Cheating with statistics

The chart below (source) is a good example of “axis”. The drop in life expectancy looks huge, but upon closer inspection, we see the the vertical axis starts only at 72.

There is another problem with the chart: “the sharpest since World War II” is not supported by the data.

One way to bring out the significance of the message, and support the WWII point is to show the annual change (not the absolute number) in life expectancy since 1940.

Trying to understand vaccine effectiveness

Here in Israel we are ahead of most other countries in terms of vaccination and the prevalence of the delta variant. After almost zero cases, the count is starting to creep up again. There is a lot of confusing data going around and it is surprising to me that the scientific community does not have a generic approach to evaluate the effectiveness of vaccines.

Last night the following table appeared on the TV news. Severe cases by age category and vaccination status. But these absolute numbers cannot be taken at face value.

Source: https://twitter.com/arad_nir/status/1416832997597265933/photo/1

“Open source” statisticians went to work and made some adjustments. The population categories are not equally big (there are more young people than old people), and the vaccination rate is not the same (older people vaccinate more). So the correct approach is to look at severe cases / million, split by vaccinated and unvaccinated. I put the results in the graph below and added the chart to the SlideMagic library.

I put the results in the graph below and added the chart to the SlideMagic library. Search for “vaccine’ in the SlideMagic app and the designs will pop up, either for use in a COVID-related presentation, or maybe something completely different that requires a similar layout.

Dashboard design

In my current (stealth) side project I need to build many dashboards to show information in different cuts and slices. For me, it is a very interesting experience as I can apply the full arsenal of my slide design experience, but now with dynamic data. I control the full stack of technology: what information to store, how to slice it, what information to show, and how to show it.

Each of the above usually reside in a different person. Management consultants spend time recutting and re-combining data manually in spreadsheets because systems can’t do it. So called “BI” applications take data from systems and spit out an endless amount of bar and pie charts in the hope that it will give some insight in where things are going. Traditional front-end web designers can make data look pretty, but don’t really understand what data is required.

The principles of a good dashboard and a good slide are completely the same. Every detail is important. What information to show, what rounding, what order, what sort of graph, what headings, bold, not bold, margins, right aligned, left aligned., how to group things, where to put subdivisions, etc. etc.

But once you get it right, it will work for a long time.

Photo by Cody Fitzgerald on Unsplash

Tiny data labels

This chart shows 2 interesting things. One, Finland was pretty happy under lock down. Two, an interesting way to put data labels on a stacked column chart. The small boxes are always a problem in a regular format. Here you get the combination of the visual effect of the size of the boxes, versus the table of the actual information. This could be inspiration for a future SlideMagic expansion.

I would do some things different though. That row of zeros at the top does not add much. The flags make the whole chart even more busy. And given that this is a comparison, I would have shown the data as a stacked bar chart.

If you were to use me as a bespoke designer, I would actually show this data on a map of Europe, color-coding different countries with maybe only the some of the 2 blue data series. The geographical clustering of the countries is interesting. In addition, I would combine it with one stat about the health impact of COVID in these countries.

If you do not have the software and/or the time to make a chart like this, the solution is easy, take off the data labels completely and make a straightforward stacked column chart.

I found this chart on Twitter, without quoting a source, the format looks like a page in some document by the European Union though.

Order of data series

Here is a (sad) chart from today’s Economist:

The Economist put the data series that carries the main message of the chart at the bottom, pushing up all the other data series. My preferred option is the other way around, put it on top. In that way you can see all other regions staying pretty much stable, while India grows strongly.

(Unrelated). India has a very large population, and you need to look at COVID in that perspective. In terms of caseload, it is still behind other regions (such as Europe). The problem is the quality of the healthcare system, and the availability of basics such as oxygen in emergency rooms. Europe could handle the load (more or less), India is in a far worse position. Also, the India stats are averages for the entire country. On a region-by-region basis, there are likely to be places with much bigger caseloads than Europe. Let’s hope that it gets better.

Legends can be confusing

Some perspectives by @clauswilke:

Slides on redundant coding.https://t.co/miqrLROikZ#rstats #dataviz pic.twitter.com/m1H34F2Zuk

— Claus Wilke (@ClausWilke) April 14, 2021

He is right. Legends can be confusing and are prone to errors, when possible, put the data label immediately next to the line.

Making sense of Israeli vaccination data

Here in Tel Aviv, I was lucky enough to receive my second vaccination with the Pfizer COVID-19 vaccine. The whole world is watching us:

• High vaccine availability

• Advanced healthcare infrastructure, with a centralized IT system (any medical professional can punch in my ID number in her computer and get all my medical records on the spot, this would raise some privacy issues in other countries)

• (Unfortunately) we are set up to deal with national crises and get organised quickly

There is lots of data available, cases, hospitalizations, difficult cases, casualties, by age, religious background, location, total cases, new cases, etc., etc. And everyone is looking at the top line number, will the big case graph go down and can we declare victory over the virus. Unfortunately so far, it stays more or less stable (at high levels).

This is a typical case of data overload. If you want to see whether the vaccine works you need to compare 2 things like for like: people who got vaccinated, and people who did not. And when you do that (pretty much like a clean medical trial), it shows that the vaccine is overwhelmingly effective, the same size is just not the entire Israeli population.

One such example is hospital admission data from a Tel Aviv hospital. Not millions of people, but a small, isolated group that you can compare. The original chart is here:

I did a quick makeover of this slide in SlideMagic.

• Colours are consistent

• Everything is properly spaced

• A better way to communicate the ‘1’ exception case

But this is the raw data, mainly of interest to scientists / statisticians. The average person just looks at the big blue “2” next to “442”. You can simplify things a bit more, see the following chart:

What did I do?

• Use a data chart instead of a table (bar charts are best for comparing)

• Lump the 7 days before and 7 days after data together, they are almost the same

• Change the metric to something that people are used to, everyone talks in terms of “vaccine efficacy is x%”. I reworked the numbers to reflect that.

I included these vaccination charts in the online SlideMagic slide template bank (click on the images), or simply search for ‘vaccination’ in the desktop app to use charts like this in your own presentation.

Stack charts with tighter grid integration

Stack charts are very useful. So useful in fact, that SlideMagic does not support pie charts (by design).

They are very easy to make in Excel, but using them straight in a presentation is tricky. First there is the overall formatting of the chart, then there is the legend which is never connected to the chart itself, and does not leave enough space for text other than ‘new’, ‘old’.

I just overhauled the stack chart in SlideMagic and forced to be tightly integrated with the slide grid. Adding/deleting rows to your slide will add/delete data series to your stack chart. Furthermore I have actually removed the legend from the stack chart shape itself, what is left is only the option to add lines that point to boxes outside the chart. This gives you total freedom to do whatever you want with the chart legend, small, big, or even huge text boxes. Everything lines up, you can even fit stack charts in tables if you want.

The charts below give you a sense of what the new engine does:

The old stack charts will continue to work in SlideMagic for the moment. If your charts have them, you can edit them. If you want to make new ones, click <SHIFT> + <STACK> and you can still make them. An old stack chart can instantly be converted into a new one by selecting it and clicking the <STACK> icon.

Stack charts in the template database are still in the old format, I will convert them over the coming weeks to the new format.

Stack charts convert to native Excel charts when saving your presentation as a PowerPoint file (the connecting legend lines are still missing for the moment). In PDF, you have exactly “what you see is what you get”.

Creative with bar labels

Below a screenshot from an Economist instagram post:

The labels of the first 2 bars have been placed over the bars themselves to save space: there is now more room for the bars themselves. Other labels to the right of the bars.

I am not a fan:

• The white over red of the top labels is hard to read

• There is no nice and simple list of the top players, aligned in a consistent way

• The names inside the chart area makes it harder to relate the bar to the axis

• (I also prefer to put data labels in the chart rather than having a very imprecise value axis)

Here is a quick illustration of a bar chart in SlideMagic (The Eonomist did not provide the exact values, hence the dummy data).

How to make a source of change waterfall chart (Apple quarterly results)

In between the election news: waterfall charts….

Waterfall charts are a great tool to explain the difference between 2 scenarios. In SlideMagic, they are really easy to create. Below is one I put together quickly with data from Apple’s 2020 Q4 earnings result, and a photo I found using SlideMagic’s built-in Unsplash image search. Notice how I opted for an unusual vertical waterfall, to create more space for the axis labels.

Some people would argue that you could make the chart even clearer by breaking the axes: showing them as ‘5.6’ and ‘4.7’ for example. Yes, it would highlight the deltas better, but in general, I think manipulating axes, well, manipulates the message. The fact that the changes are relatively small to the total is part of the message.

I reshuffled the rows a bit to group the decreases and increases. That makes it more clear in one sense, but less clear in another. Your choice.

\How do you go about making such an analysis? I put my numbers in a Google Sheet that you can view yourself.

1. Enter the data for the 2 comparable quarters in 2 columns. Add the totals as calculations rather than hard-coded numbers to check that you did not make any typos. (The blue cells are the one that I type in, the white ones are calculations).

2. Create space between the 2 columns

3. Pull numbers from the input that you consider drivers. You see that I deviated a bit from the way the input was presented:

   1. Divided billions by thousands to make it more readable

   2. I use % gross margin rather than absolute COGS and profit numbers

   3. R&D: absolute number, SGA, % of sales

4. Recalculate the operating income with just these drivers (line 37), it is crucial that you get this right, double check with the input.

5. Now start varying your drivers one at a time, and recalculate the operating income in the scenario that just that one variable would have changed (see the green numbers in the spreadsheet).

6. Finally, check whether the component variations add up to the total variation you need to explain (in this case, I was lucky). If you are not, you need to allocate the non-explained differences to the factors somehow.

It is important to keep in mind that these spreadsheet figures are just spreadsheet figures. The change in product gross margin for example is probably not independent from the change in product mix (fewer phones, more laptops). Also there is a small rounding issue (the rounded vales do not add up to 14.8). I would solve that by chopping the biggest factor (-1.7 to -1.6). It is always distracting when small rounding errors create inconsistent numbers on your slide.

Users of SlideMagic can access the waterfall charts with a search for ‘apple’ in the desktop app.

Log scales?

With all the talk about exponential growth of the virus, logarithmic scales are popping up in graphs everywhere.

What is a logarithmic scale? Unlike those on a linear scale, the units on a logarithmic scale change. See the chart below.

The result is that the normally speaking rapidly growing line 10^x now appears as a simple straight line.

Exponential functions can be hard to graph, analyse and compare. Toning down the scale makes things more manageable. I remember in high school, I used log mm paper to plot graphs from physics or chemistry experiments. By measuring the incline of the line, I could estimate exponential coefficients, and compare them.

While logarithmic scales are a great practical tool for scientists, I think they are less useful in presentations to a more general audience. “Look at this straight line, but in order to understand how fast tings are really growing, look at the small numbers that reveal the axis measurements”. People simply don’t grasp the concept of a logarithmic scale. If the virus grows exponentially, well, show an exponential line.

If you need to compare exponential growth, make a bar chart of the growth rates, rather than drawing straight lines on logarithmic scales.

Architecture diagrams

I am starting to experiment with different chart types in SlideMagic. One experiment: IT architectures that consist of users, servers, databases, clouds and lots of lines.

The built-in icon search, combined with the new line drawing feature does a pretty good job actually. And while SlideMagic is not a dedicated tool to design network architectures, it might actually force you to make better architecture diagrams in presentations. Let me explain.

Detailed network diagrams have the same problem as detailed spreadsheets when it comes to presentations. They are project work tools to run analysis and plan work, they are not tools for communication. When I need to make a data chart, I always disconnect from the spreadsheet and resist the temptation to copy-paste. Instead, I pick the 10 numbers that matter, round them up to the relevant precision, and plop them in a very simple bar/column chart that tells the story.

The same is true for IT architectures. If you want to present an architecture overview on a slide, that slide needs to be understood almost immediately when putting it up (like all slides in your deck). If tangled connections, boxes, servers make that hard, then the only thing your slide communicates is that your architecture is complex, not much more.

Again, disconnect from the working papers. Think about your message: ‘my architecture has 3 layers’, ‘my system connects the systems of 15 suppliers’, ‘my system is entirely on premise’, whatever that message is, make a simple chart that supports it.

Remember, presentation slides are usually not project briefings for network installers.

Waterfall charts in SlideMagic!

Finally, they have arrived. Waterfall charts in SlideMagic. Everything lines up with other elements in your slide. Super easy to make and edit, super easy to convert to editable PowerPoint / Excel charts if needed. Download version 2.4.7 of SlideMagic to try it out (both for Windows and Mac). This is a brand new module in the app, please let me know if you experience any issues or have other suggestions.

Chart makeover: where do people get infected with COVID-19

Israel is experiencing a very strong second wave of the virus. Its health ministry recently published data about where people get infected.

This graph does not tell the entire picture, I tried making a quick slide in SlideMagic:

What did I add?

• Providing the overall context: for many patients it is not known where they are infected, and many get infected at home (which are probably secondary infections)

• There is still important data missing. The most important one is how many people in total actually visit a place. Millions of people visit schools, thousands probably visit gyms and places

• We need to understand the impact on secondary infections (how big are the typical households that these people are coming from).

• Then there is the question about impact to society…

This SlideMagic slide is free, you can download it here. It is clearly an example of an analysis slide, rather than a visual to be presented to a large audience. While I am not a big fan of stretched 16:9 layouts, in this case I had to go for it to create space.

PS. My opinion re. the strong second wave in Israel? Yes, Israel got the virus under control and then reopened too quickly (school were the main source of infection initially). But, in the end I believe any country re-opening will go through the same process, may just a bit slower. I think Israel is 1-2 months ahead of other countries re-opening.

How to design management dashboards

The number of app installs of SlideMagic 2.0 is still small, but the graph has a similar shape as the exponential graphs we all have gotten used to over the past weeks.

Modern analytics tools allow you to track literally everything under the sun in your app and/or web site. Instant information overload supported by colourful graphs that look good, but don’t say much. This overload of data is similar to the ones I would encounter as a consultant at McKinsey. And now, 15+ years later, I find myself following a similar approach to making sense of it for my own app.

Most case examples about analytics are built for established apps and web sites with huge customer flows you can micro analyse whether the check out button should br green or red. SlideMagic is not there yet.

• I find myself going through a certain cycle. It starts with a basic question, “how many people did actually install the app”, which results in a daily manual routine to find the latest number, which then gets translated into a proper query in an analytics app. I check whether my analytics tool is consistent with the numbers I can dig out of my own server. Slowly, slowly, I get a sense of how the app behaves with a consistent set of data that I can recognise.

• Slowly, slowly, I start adding more questions to the picture, and make sure that I keep a picture of how they relate.

• Each factor has a specific visualisation: some are lines, some are bars, some uniques, some totals, some cumulative, you need to play around with it.

The key factor I need to work on now is a very specific one. Of the users that know of SlideMagic, installed it, tried it a first time, then tried it out seriously (now we are down to small numbers), of those, can I get a handful of users that really, really start using it. If we get that final step to work, I am confident that the previous steps in the funnel will work itself out.

Work in progress.

Photo by YIFEI CHEN on Unsplash

Bar versus column charts

Sparked by this tweet:

Hmm. Might need a log scale on this one. pic.twitter.com/Qgn2GLRWPG

— Benedict Evans (@benedictevans) November 6, 2019

My guideline:

• Columns to show trends over time. The shape mimics that of a line chart, you don’t need much space for the column labels (usually years, or months)

• Columns for breakdowns. More horizontal space for complicated labels, and a stacked column is a more natural format than stacked bars.

• Bars to rank things. The shape mimics a “top 10” top to bottom list, and you can make more space for labels that usually describe things

In this case: bars are better than columns.

Photo by Sophie on Unsplash