voluntaryXchange

Best Explanation of Degrees of Freedom I’ve Ever Heard

It’s about geometry, rather than stats, but it works for me.

Why is a 3-legged stool always steady?

Think of it this way:

1. If you hold a cane in the air, you can move it in any direction, twirl it, and so on. Its motion isn't constrained at all. That is, the top of the cane can move freely in three dimensions.
2. If you put (and keep) one end on the ground, now its motion is constrained: you can't lift it, or rotate it... although you can swing the top around in a variety of different arcs. That is, the top of the cane can move freely in two dimensions.
3. If you connect the tops of two canes together and place the other ends on the ground, you can still move the tops, but only along a single (straight) arc, back and forth. That is, the tops of the canes can move freely in one dimension.
4. If you try the same trick with three canes, now you can't move the tops at all. This is basically what's happening with a three- legged stool. The tops of the cans can move in zero dimensions... which is to say, they can't.

Each time you add a cane, you remove one dimension in which the top can move freely - that is, each new cane removes one 'degree of freedom'.

Via bookofjoe.

Technorati Tags: degrees,freedom,3,three,legged,stool

Excel Tip # 15: Restrict Users Free Space

Got a worksheet whose blank space you don’t want users to use for scratch work?

Open your Developer menu† (you may need to add this through Excel Options). Then paste this code into a module for the file (you may need to create one‡).

Private Sub Worksheet_Activate()

  'Set/restrict sheet's scroll area.

  Me.ScrollArea = "A1:G15"

End Sub

One drawback of this is that you will now have to save as an XLSM file, and your users will have to enable macros when they open it.

† To display the Developer Tab, click on the Office 2007 button in upper left corner, then on options, and select Developer.

‡ Click the Developer tab, then “Visual Basic”. A window will open. On the left, right-click VBAProject and choose “Insert” then “Module”. Paste the code above into the new window that opens.

Technorati Tags: excel,tip,15,restrict,free,space

Word Tip # 19: Cheatsheet for Alt Codes

Do you enter symbols into Word documents?

Hold down the ALT key and use the numeric keyboard to enter many symbols quickly.

Via TechRepublic’s 10 Things.

Technorati Tags: word,tip,19,alt,code,symbol

Page Views vs. Hits

I’ve been looking over my traffic. Hits are not what they used to be.

My host tracks my hits: I’m down to about 2400 per month, or 29K per year. Each of their hits is somewhat more than 1 page view, so figure there are perhaps 40K page views there.

But, I feed 228 people that get every post. That works about to about 120K page views per year.

All told, about 160K page views per year, of which only a about a quarter count as hits.

Technorati Tags: page,view,hits,feed

A Quick and Funny Video

What if your pilot faked falling asleep?

Via Windows Secrets.

Technorati Tags: pilot,asleep

100% Tariff On Paper Clips

OMFG.

The eleven billion paper clips used each year in this country are made largely in the United States, perhaps because there are 100%+ tariffs on the import of paper clips from abroad.

Via Marginal Revolution.

Technorati Tags: paper,clip,tariff

Tune In Tonight

If you can get it, tonight’s performance of Midsummer Night’s Dream by the Tony-award winning Utah Shakespearean Festival will be broadcast live on BYUtv at 7:30 MDT.

Cox Cable or the two satellite companies look like your best best outside of the intermountain west.

Technorati Tags: utah,shakespearean,festival,byutv,midsummer,night's,dream

Coulda, Shoulda, Woulda

I wish I’d posted this thought last week. Anyway …

I commented on the Accuweather site last week that Hurricane Irene seemed likely to be like 1972’s Hurricane Agnes.

In a great example of the recency effect, Heather Buchman, the meteorologist who wrote the piece compared the potential effects of Irene to a list of other hurricanes drawn from the last 22 years: Bertha ‘96, Bob ‘91, Fran ‘96, Floyd ‘99 and Hugo ‘89.

Agnes held the record for most expensive Hurricane for 7 years. Most of its damage was from rains, and flooding.

Just like Irene:

Many of the worst effects arose from rains that fell inland …

… [Vermont] Gov. Peter Shumlin called it the worst flooding in a century.

Technorati Tags: irene,agnes,hurricane

Life Expectancy Pitfalls

The U.S. often gets beat up in international circles for our low life expectancy relative to other developed countries. Here are links to a couple of caveats about that.

Some information about how premature infants are counted can be found in this piece from the Centers for Disease Control. Most of this is about how infant mortality is measured across countries, and in some countries a prematurely born baby is not counted as a person unless it is big enough or survives long enough. This will clearly influence life expectancy statistics if some countries (like the U.S.) essentially count a lot of lifetimes of zero years.

Some information about how homicide rates have been higher in the U.S. for centuries, which will lead to lower life expectancy, can be found here.

Technorati Tags: life,expectancy,homicide,premature,birth

Airline Network Maps

Don’t you just love these:

This is the local …

Visualnews has images for all the other major airlines too.

Via Newmark’s Door.

Technorati Tags: airline,network,map