A little coffee on the prairie

Posted on 4 November 2009 by John

I was reading Little House on the Prairie with my youngest daughter the other day. Here’s a passage that surprised me.

Then Pa brought water from the creek, while Mary and Laura helped Ma get supper. Ma measured coffee beans into the coffee mill and Mary ground them.

I’d read this book with my other children and hadn’t given this part a thought. This time I thought about how odd it was that they had coffee. At this point the Ingalls family was moving from Wisconsin to Kansas some time in the 1870’s. The family of five and all their worldly goods were packed into a covered wagon. They shot wild game for food. They gathered water from creeks. And yet they had coffee.

Coffee doesn’t grow in the continental United States. It grows in the tropics at high altitudes. These settlers living off the land in the middle of nowhere had some coffee beans that had been imported from thousands of miles away. It’s interesting to think that despite all that they lacked, they had these tropical beans and apparently took them for granted. Said another way, of all the benefits of civilization, coffee made the short list of things settlers chose to take with them.

Manage your project portfolio

Posted on 3 November 2009 by John

Most books on project management are written for someone managing one project at a time, working with a team of people who only work on that project. Some companies work that way, but certainly not all do. I’ve seldom worked that way. At one point I “managed” so many projects that I could not tell you the exact number without looking at my list.

Johanna Rothman’s new book Manage Your Project Portfolio (ISBN 1934356298) addresses the challenges of managing not just one project but a portfolio of projects. The book does not tell you how to work multiple simultaneous projects but rather how to get away from working on multiple projects by prioritizing them and working on one at a time.

Here are a couple quotes from the beginning of the book.

Quite often I have the chance to visit a team to help management figure out why they’re not making much progress. When I get there, I find a small team working on more projects than they have people.

Multitasking occurs when managers don’t make decisions about which projects to do first, second, third, last, and even more important, never.

I wish I could have read Johanna Rothman’s book a decade ago. On the other hand, I would not have appreciated the book as much a decade ago. Still, it might have helped me prevent some of the errors I made. I hope that many people will read the book before they become overwhelmed and appreciate its wisdom.

Yet another view of the negative binomial

Posted on 3 November 2009 by John

A while back I wrote a post on three views of the negative binomial distribution. This post adds a fourth view.

One of the shortcomings of the Poisson distribution is that its variance exactly equals its mean. It is common in practice for the variance of count data to be larger than the mean, so it’s natural to look for a distribution like the Poisson but with larger variance. We start with a Poisson random variable X with mean λ, but then we make λ itself random and suppose that λ comes from a gamma(α, β) distribution. Then the marginal distribution on X is a negative binomial distribution with parameters r = α and p = 1/(β + 1).

The previous post said that the negative binomial is useful because it has more variance than the Poisson. The derivation above explains why the negative binomial should have more variance than the Poisson.

For details, see updated notes on the negative binomial distribution.

Zero-knowledge password management in JavaScript

Posted on 2 November 2009 by John

The most recent guest on Jon Udell’s Interviews with Innovators podcast was Marco Barulli. Barulli discusses Clipperz, a zero-knowledge password management application. The software encrypts passwords (or arbitrary text) using client-side JavaScript. Your data is encrypted on your computer and the encrypted version is uploaded to the Clipperz server. When you want to retrieve your data, the encrypted data is downloaded to your computer and decrypted there. Your unencrypted data never leaves your computer.

For more information, see the article on Jon Udell’s blog or listen to the podcast. Even if you’re not interested in using the Clipperz product, you may find the discussion of JavaScript and cryptography techniques interesting.

PowerShell 2.0 for Windows XP etc.

Posted on 2 November 2009 by John

PowerShell version 2.0 shipped with Windows 7 and with Windows Server 2008 R2, but it only recently became available for other versions of Windows.

The release of PowerShell 2.0 has been more like a leak than a product launch. The announcement page hardly reads like an announcement. The title reads “Description of the Windows Management Framework on Windows XP, Windows Server 2003, Windows Vista, and Windows Server 2008.” What’s this “Windows Management Framework”? I’ve never heard of that. I just want the new PowerShell. The first time I saw this page was when someone sent me a link saying PowerShell 2.0 was available for XP. I thought they’d sent me the wrong link by mistake because I didn’t see anything about PowerShell at first. Only if you scroll down to the middle of a long page can you see links to download PowerShell.

I expected something more like the following.

PowerShell 2.0 Released

Download for your platform:

XP
Vista (32 bit, 64 bit)
Server 2003 (32 bit, 64 bit)
Server 2008 (32 bit, 64 bit)

Related links:

Month: November 2009