The job of a tennis line judge can be though when you have to judge the difference of a few millimeters as a ball speeds by. Sure, it’s easy to complain about bad calls at home, where we get to see replays in slow motion, but it’s more challenging in real life. The Wall Street Journal provides a bit of the experience with an interactive game. Watch video clips from a line judge’s point of view, and try to make the right call.

Similar in spirit to dot density maps we’ve seen before, this one from Kyle Walker, an assistant professor of geography at Texas Christian University, uses immigrant data from the American Community Survey to show the makeup of immigrant America.

Each dot represents approximately 20 immigrants in that Census tract from a given region, and the dots are placed randomly within Census tracts. The project was inspired by other interactive dot map implementations including The Racial Dot Map at the University of Virginia; Ken Schwenke’s Where the renters are; and Robert Manduca’s Where Are The Jobs?.

Color represents origin, such as red for Mexico, cyan for South Asia, and green for Southeast Asia.

The tools used to make this map? A combination of R, QGIS, ArcGIS, and Python for data processing and Mapbox for the web presentation.

Dylan Selterman, a psychology lecturer at the University of Maryland, presents the above problem—a variation of the Prisoner’s Dilemma—as extra credit on his exams. He’s done this since 2008, but a student recently posted a picture of the question and it spread through the networks of social media.

The question amuses, but naturally, it evokes another: How do students answer? For Quartz, Selterman describes the results and the overarching moral lessons we can learn from them.

It’s important to note that most students in my class (around 80% each semester) end up choosing two points. While many students choose the “rational” six-point option, they are still in the minority.

I believe this is because most people do understand the importance of being communal. In other words, most people are happy to behave in a way that benefits others around them.

The problem is that there is still many who don’t. With the exception of one year, no class received extra points, because more than 10 percent of students selected the greater six-point option.

Robin Weis recollected her dating record over the past eight years, and made a simple chart to show the data. Purple represents an established relationship, green represents a causal one, and black lines represent first dates. Darker shades of purple and green represent days We saw the corresponding person in real life.

The short anecdotes for each record make it.

Named after the grid system Thomas Jefferson used to apportion land acquired through the Louisiana purchase, the Jefferson Grid Instagram account highlights remnants of the system through satellite shots from Google Earth. Each picture is the land that fits into one square mile.

The most fun ones more me are the desert shots. It’s a square mile of development and just dirt everywhere else.

The Minimum Wage Machine by Blank Fall-Conroy places minimum wage in the context of seconds and pennies. Turn the crank, and every 4.5 seconds a penny drops out of the plexiglass case, which is the equivalent of eight dollars an hour. Stop cranking and you get nothing. [via Boing Boing]

NBA basketball teams have tracking systems installed in their arenas called SportVu, essentially a system of cameras pointed at the court to track player movements. Some of that data is browsable through the NBA site, but there’s understandably no direct download link. However, there is an API. Savvas Tjortjoglou wrote a thorough tutorial on how to grab data via the API and plot it Python.

This will be fun.

Norse monitors cyber attacks in real-time. This is their map of what’s going on. (All I hear is pew, pew, pew when I watch it.) [via Boing Boing]

I’m doing a Reddit AMA tomorrow hosted by the DataIsBeautiful subreddit. It’ll be at 1:30pm EST on August 27, 2015.

In case you’re unfamiliar with the AMA (ask me anything), it’s just a fun Q&A thing, where you ask me questions on Reddit, and I pause to think of something good to say. I might type some answers.

Ask me about visualization, data, blogging, graduate school, my hate of commuting, my kid’s poop habits, beer, or whatever else. I’m game.

This map of subway complaints in Madrid isn’t geographically relevant to me, but the encoding scheme is interesting.

Each spot represents a station, and a collection of concentric circles represent the various types of complaints for that station. Larger circles represent more complaints, and more circles represent more complaint types.

So for someone in charged of repairs, maintenance, and overall system performance could pretty quickly figure out the problem areas and what actions to take.

The New York Times got me to watch an interview with Justin Bieber in it multiple times. Along with (mostly) Diplo and Skrillex, a visual layer set on top of the video interview further explains what the musicians are talking about.

Here, just watch it.
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Jim Davies for Nautilus on our unconscious bias and how being non-biased leads to more bias:

And the more we convince ourselves that we don’t have certain biases, the more likely we are to exhibit them. If we believe we’re good people, for example, we may stop trying to be better and may be more likely to act indecently. Similarly, if we think we’re smart, we might skip studying for a test and give ignorant answers. In general, if we believe we’re unbiased, we’re giving ourselves permission to be biased.

I don’t know. Seems biased.

Body mass index is often used as a way to set weight classes of underweight to obese, but the measurement is likely too basic. From the New York Times:

The illustrations here were created from scans of six people, who were all 5 feet 9 inches tall and 172 pounds. This means that though their bodies look very different, they all have exactly the same body mass index, or B.M.I. At 25.4, technically each of them could be considered overweight.

And Dwayne “The Rock” Johnson is classified as obese.

Of course, this applies to most indexes and classifications. You try to get it to work for as many as people, places, or things as you can, but there’s always going to be exceptions and more information to be had.

Passwords are annoying, which is why so many people use passwords that are less than secure. Maybe the keys are a bit shorter than they should be, match a word in the dictionary, or are repeats across services. In these cluster of passwords, patterns become obvious.

Marte Løge, for her master’s thesis at Norwegian University of Science and Technology, wondered if similar rules applied to Android lock screen patterns. Dan Goodin for Ars Technica explains:

Data breaches over the years have repeatedly shown some of the most common passwords are “1234567”, “password”, and “letmein”. Løge said many ALPs suffer a similar form of weakness. More than 10 percent of the ones she collected were fashioned after an alphabetic letter, which often corresponded to the first initial of the subject or of a spouse, child, or other person close to the subject. The discovery is significant, because it means attackers may have a one-in-ten chance of guessing an ALP with no more than about 100 guesses. The number of guesses could be reduced further if the attacker knows the names of the target or of people close to the target.

So wait a minute. What’s a lock screen?

I have no idea what’s going on here, and I prefer to keep it that way.