Tag: blog

On procrastination, or why too good can be bad

Illustration: a plastic gun and letters that say "bang"
~ Boris Gorelik ~ Leave a comment

I’m a terrible procrastinator. A couple of years ago, I installed RescueTime to fight this procrastination. The idea behind RescueTime is simple — it tracks the sites you visit and the application you use and classifies them according to how productive you are. Using this information, RescueTime provides a regular report of your productivity. You can also trigger the productivity mode, in which RescueTime will block all the distractive sites such as Facebook, Twitter, news sites, etc. You can also configure RescueTime to trigger this mode according to different settings. This sounded like a killer feature for me and was the main reason behind my decision to purchase a RescueTime subscription. Yesterday, I realized how wrong I was.

RescueTime logo

When I installed RescueTime, I was full of good intentions. That is why I configured it to block all the distractive sites for one hour every time I accumulate more than 10 minutes of surfing such sites. However, from time to time, I managed to find a good excuse to procrastinate. Although RescueTime allows you to open a “bad” site after a certain delay, I found this delay annoying and ended up killing the RescueTime process (killing a process is faster than temporary disabling a filter). As a result, most of my workday stayed untracked, unmonitored, and unfiltered.

So, I decided to end this absurd situation. As of today, RescueTime will never block any sites. Instead of blocking, I configured it to show a reminder and to open my RescueTime dashboard, as a reminder to behave myself. I don’t know whether this non-intrusive reminder will be effective or not but at least I will have correct information about my day.

Against A/B tests

~ Boris Gorelik ~ 1 Comment

Traditional A/B testsing rests on a fundamentally flawed premise. Most of the time, version A will be better for some subgroups, and version B will be better for others. Choosing either A or B is inherentlyinferior to choosing a targeted mix of A and B.

Michael Kaminsky locallyoptimistic.com

The quote above is from a post by Michael Kaminsky “Against A/B tests“. I’m still not fully convinced by Michael’s thesis but it is very interesting and thought-provoking. 

Useful redundancy — when using colors is not completely useless

~ Boris Gorelik ~ Leave a comment

The maximum data-ink ratio principle implies that one should not use colors in their graphs if the graph is understandable without the colors. The fact that you can do something, such as adding colors, doesn’t mean you should do it. I know it. I even have a dedicated tag on this blog for that. Sometimes, however, consistent use of colors serves as a useful navigation tool in a long discussion. Keep reading to learn about the justified use of colors.

Pew Research Center is a “is a nonpartisan American fact tank based in Washington, D.C. It provides information on social issues, public opinion, and demographic trends shaping the United States and the world.” Recently, I read a report prepared by the Pew Center on the religious divide in the Israeli society. This is a fascinating report. I recommend reading without any connection to data visualization.

But this post does not deal with the Isreali society but with graphs and colors.

Look at the first chart in that report. You may see a tidy pie chart with several colored segments. 

Pie chart: Religious composition of Israeli society. The chart uses several colored segments

Aha! Can’t they use a single color without losing the details? Of course the can! A monochrome pie chart would contain the same information:

Pie chart: Religious composition of Israeli society. The chart uses monochrome segments

In most of the cases, such a transformation would make a perfect sense. In most of the cases, but not in this report. This report is a multipage research document packed with many facts and analyses. The pie chart above is the first graph in that report that provides a broad overview of the Israeli society. The remaining of this report is dedicated to the relationships between and within the groups represented by the colorful segments in that pie chart. To help the reader navigating through this long report, its authors use a consistent color scheme that anchors every subsequent graph to the relevant sections of the original pie chart.

All these graphs and tables will be readable without the use of colors. Despite the fact that the colors here are redundant, this is a useful redundancy. By using the colors, the authors provided additional information layers that make the navigation within the document easier. I learned about the concept of useful redundancy from “Trees, Maps, and Theorems” by Jean-luc Dumout. If you can only read one book about data communication, it should be this book.

Microtext Line Charts

~ Boris Gorelik ~ 2 Comments

Why adding text labels to graph lines, when you can build graph lines using text labels? On microtext lines

richardbrath

Tangled Lines

Line charts are a staple of data visualization. They’ve existed at least since William Playfair and possibly earlier. Like many charts, they can be very powerful and also have their limitations. One limitation is the number of lines that can be displayed. One line works well: you can see trend, volatility, highs, lows, reversals. Two lines provides opportunity for comparison. 5 lines might be getting crowded. 10 lines and you’re starting to run out of colors. But what if the task is to compare across a peer group of 30 or 40 items? Lines get jumbled, there aren’t enough discrete colors, legends can’t clearly distinguish between them. Consider this example looking at unemployment across 37 countries from the OECD: which country had the lowest unemployment in 2010?

unemployment_plain

Tooltips are an obvious way to solve this, but tooltips have problems – they are much slower than just shifing visual attention…

View original post 1,323 more words

On the importance of perspective

~ Boris Gorelik ~ Leave a comment

Stalin was a relatively short man, his height was 1.65 m. Khrushchev was even shorter, his height was 1.60. It seems that the difference wasn’t enough for the official Soviet propaganda of that time. Take a look at this photo. We can clearly see that Stalin is taller than Khrushchev.

stalin.png

Do you notice something strange? Take a look at the windows in the background. I added horizontal and vertical guides for your convenience.

Screen Shot 2018-11-05 at 8.38.08

Now, look what happens when we fix the horizontal and vertical lines

Screen Shot 2018-11-05 at 8.39.03

Now, Khrushchev is still shorter than Stalin but not by that much.

Data visualization in right-to-left languages

Line chart that uses Arabic text and numerals
~ Boris Gorelik ~ 1 Comment

If you speak Arabic or Farsi, I need your help. If you don’t speak, share this post with someone who does.

Right-to-left (RTL) languages such as Hebrew, Arabic, and Farsi are used by roughly 1.8 billion people around the world. Many of them consume data in their native languages. Nevertheless, I have never seen any research or study that explores data visualization in RTL languages. Until a couple of days ago, when I saw this interesting observation by Nick Doiron “Charts when you read right-to-left“.

I teach data visualization in Israeli colleges. Whenever a student asks me RTL-related questions, I always answer something like “it’s complicated, let’s not deal with that”. Moreover, in the assignments, I even allow my students to submit graphs in English, even if they write the report in Hebrew.

Nick’s post made me wonder about data visualization do’s and don’ts in RTL environments. Should Hebrew charts differ from Arabic or Farsi? What are the accepted practices?

If you speak Arabic or Farsi, I need your help. If you don’t speak, share this post with someone who does. I want to collect as many examples of data visualization in RTL languages. Links to research articles are more than welcome. You can leave your comments here or send them to boris@gorelik.net.

Thank you.

 

The image at the top of this post is a modified version of a graph that appears in the post that I cite. Unfortunately, I wasn’t able to find the original publication.

Can error correction cause more error? (The answer is yes)

~ Boris Gorelik ~ Leave a comment

This is an interesting thought experiment. Suppose that you have some appliance that acts in a normally distributed way. For example, a nerf gun. Let’s say now that you aim and fire the gun. What happens if you miss by some amount of X? Should you correct your aim in the opposite direction? My intuition says “yes.” So does the intuition of many other people with whom I talked about this problem. However, when we start thinking about this problem, we realize that the intuition is wrong. Since we aim the gun, our assumption should be that the deviation is zero. A single observation is not sufficient to reject this assumption. By continually adjusting the data generating process based on a single observation, we reduce the precision (increase the dispersion).
Below is a simulation of adjusted and non-adjusted processes (the code is here). The broader spread of the adjusted data (blue line) is evident.

Two curves. Blues: high dispersion of values when adjustments are performed after every observation. Orange: smaller dispersion when no adjustments are done.

Due to the nature of the normal random variable, a single large accidental deviation can cause an extreme “correction,” which in turn will create a prolonged period of highly inaccurate points. This is precisely what you see in my simulation.
The moral of this simple experiment is that you shouldn’t let a single affect your actions.

 

“Any questions?” How to fight the awkward silence at the end of a presentation?

Questions?
~ Boris Gorelik ~ 2 Comments

If you ever gave or attended a presentation, you are familiar with this situation: the presenter asks whether there are any questions and … nobody asks anything. This is an awkward situation. Why aren’t there any questions? Is it because everything is clear? Not likely. Everything is never clear. Is it because nobody cares? Well, maybe. There are certainly many people that don’t care. It’s a fact of life. Study your audience, work hard to make the presentation relevant and exciting but still, some people won’t care. Deal with it.

However, the bigger reasons for lack of the questions are human laziness and the fear of being stupid. Nobody likes asking a question that someone will perceive as a stupid one. Sometimes, some people don’t mind asking a question but are embarrassed and prefer not being the first one to break the silence.

What can you do? Usually, I prepare one or two questions by myself. In this case, if nobody asks anything, I say something like “Some people, when they see these results ask me whether it is possible to scale this method to larger sets.”. Then, depending on how confident you are, you may provide the answer or ask “What do you think?”.

You can even prepare a slide that answers your question. In the screenshot below, you may see the slide deck of the presentation I gave in Trento. The blue slide at the end of the deck is the final slide, where I thank the audience for the attention and ask whether there are any questions.

My plan was that if nobody asks me anything, I would say “Thank you again. If you want to learn more practical advises about data visualization, watch the recording of my tutorial, where I present this method  <SLIDE TRANSFER, show the mockup of the “book”>. Also, many people ask me about reading suggestions, this is what I suggest you read: <SLIDE TRANSFER, show the reading pointers>

Screen Shot 2018-09-17 at 10.10.21

Luckily for me, there were questions after my talk. Luckily, one of these questions was about practical advice so I had a perfect excuse to show the next, pre-prepared, slide. Watch this moment on YouTube here.