voluntaryXchange

A Money Quote: Galloway on WeWork

Scott Galloway:

People showed up with this core competency called … math … and said “No!” to this.

The context of this is the implosion of the IPO for WeWork over the last two weeks, and as of yesterday, the push out of its CEO and founder.

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The details are that WeWork is a company that rents office space to startups without facilities. The founder also had a lot of pie-in-the-sky ideas about how WeWork was going to change the universe. An IPO means that a startup is fully cooked and ready to be presented to the public as a potential investment. It’s also a way for the insiders to turn all their sweat equity into liquidity they can maybe cash out. A lot of potential investors bought into the sales pitch that this one was hugely valuable. And then those emotional investors drew the thinking investors who pointed out that this is just a real estate firm with some frills, they weren’t making money on the real estate part, and the frills were merely … amusing.

A Simple Video Proving the Pythagorean Theorem

This is very clever:

The big insight — which no one told me about until I was about 45 (even though I’m a math nerd) — is that the square of a number is literally a square geometrically. Thus the 3 squares around the triangle, and the flowing liquid to prove the point.

For those who don’t recall, the Pythagorean Theorem says that the squares of the lengths of the two shorter sides of a right triangle equal the square of the length of the longer side.

FWIW: this echoes a clever proof constructed out of paper in one of Edward Tufte’s books.

Via bookofjoe.

Lotus 1-2-3, Dabo Swinney, and the Clemson National Championship

Here’s a computer detective story.

I’m not much of a football fan, but I did watch Clemson beat Alabama last night.

And they covered the personal interest story that the Clemson coach, Dabo Swinney, was a walk-on wide receiver at Alabama in 1989.

That rang a bell: I had had a student in principles when I was at Alabama (1989-1991) that they used to joke about, because he was like Rudy. This was pre-Hollywood, but even so it was an apocryphal story on college campuses — the little white kid who plugged away just to play college football.

So I checked out Swinney’s Wikipedia page, and he was a business major at Alabama when I was teaching mostly principles in their business school.

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My computer hard drive is an archive. And my digital life is far more organized than my actual one.

So, it took me about 2 minutes to find grade spreadsheets from my time at Alabama.

The thing is, they were in WK1 format, from Lotus 1-2-3 Release 3.1. These files can no longer be opened by Excel.

I went looking on the internet, and found others who’d had similar problems. This thread was very helpful.

In it, I learned the Gnumeric can still open WK1 files. Gnumeric is an open source spreadsheet, primarily used on Linux systems. I went to their site and found out they’d discontinued Windows support.

For some reason I went back and kept reading that thread. Towards the end, someone noted that you can still download the last Windows version of Gnumeric (from 2011) on SourceForge.

I downloaded it, installed it, and started opening up Lotus spreadsheets from a generation ago.

From start to finish, the whole experience took about 20 minutes. Probably less than it took to write this post.

FWIW: the thread also notes that, if you can find it for download, OpenOfficeCalc will open WK1 files as well. I didn’t check this out.

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No, I did not find William “Dabo” Swinney’s name in them. But I only found the grades for two classes, and recollect that I taught at least 7 sections over those two years.

But, I didn’t start using Lotus 1-2-3 for grades until the last semester I was at Alabama. I don’t remember what I did use before that (probably paper). But I do recall that I started using Lotus 1-2-3 because I had a TA, and that was all he knew how to use, so I let him go for it with the software he liked.

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My Favorite Pie Chart of All Time

Via I Love Charts.

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A Little Humor at Galton’s Expense

A stats joke:

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Dilbert: Correlation Isn’t Causality

A keeper for my applied classes:

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Spurious Correlations

Here’s a site that plots spurious correlations* between variables. The description indicates that these correlations are found by a data mining program rather than a person.

The above is a true spurious correlation: even though the data is measured across time, it’s hard to see that time is intimately involved in the data generation. Per capita cheese consumption is just not something I can see trending off to infinity.

I do wish there was a section that isolated spurious correlations between trending times series though. In this one, we could reasonably expect both variables to go to infinity if given enough time.

For my part, I think pairs like the second one are more critical to recognize, because there isn’t a sense in which this is ever going to go away if we get more data. In contrast, the correlation in the upper plot will probably go away if we keep plotting it year after year, as eventually per capita cheese consumption levels off or starts to decline.

* A correlation is spurious if it occurs by chance, and has nothing to do with an identifiable cause and effect.

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The Excel Artist

Tatsuo Horiuchi’s chosen medium is … Excel.

I discussed his work in my MBA class “Spreadsheet Engineering Craft” last semester.

Via Kottke.

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Excel Tip # 29: Excel’s Unusual Order of Operations

I’ve always thought this kind of funny: even people who are “bad at math” tend to have a good handle on order of operations. You know: do the exponents first, then multiplication and division, and then addition and subtraction.

It turns out that Excel violates that standard in one way. Like all things with computers though, our lack of clarity about what we’re doing is part of the problem: GIGO.

So, consider the following:

3-5=-2

You and I look at this and say: “three minus five equals minus two”. That’s correct, but it misses an important subtlety: the two occurrences of minus in that phrase are homophones — they sound the same but have different meanings!

What?

Both of those minuses are (algebraic) operators. But the minus on the left operates on two numbers (i.e., it’s binary), while the operator on the right operates on one number (i.e., it’s unary).

A better way to state that equation would be “three subtract five equals negative two”. That’s correct because subtraction requires you to know both numbers, while negation only requires you to use one.

So, what does Excel do? In order of operations, most people lump negation together with subtraction. Excel does not: it does negation before even exponents.

This can very easily make a difference in your Excel calculations. Consider this

-3^2

If you evaluated this by hand, you’d do the exponent before the minus, like so:

-3^2 = -(3^2) = –9

But, not Excel. Excel says that it makes a difference whether that minus is used for subtraction or negation: subtraction would go after exponentiation, but negation would go before exponentiation. So, Excel does it this way:

-3^2 = (-3)^2 = 9

Wow. There’s got to be a world of hurt in the business world from that one.

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Excel Tip # 26: Selecting a Huge Range

I frequently need to select a large range that goes off one or both sides of the screen.

This is an easy thing to do if the range is continuous: just hold down SHIFT and use your arrows, END and HOME keys.

But, it’s a pain if your range isn’t continuously filled with data. Then Excel will stop at each blank.

Susan Harkins at TechRepublic offers a solution to this, provided that you know the address of the bottom right cell of your range:

• Click in the top left of your range.
• Click F5.
• Enter the cell at the bottom right.
• Hold down SHIFT and press OK.

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