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Sunday, Nov 8, 2009
Mr Smith
Published Letters: 218 Editor's Choice: 8
Just a quick note regarding how to properly interpret a confidence interval. The theory behind it goes like this: You are searching for a number that truly exists, in this case the percentage of people saying they will vote for candidate X. This is called the population proportion. You take a random sample (because you can't sample everybody) and figure out what proportion in your sample say they will vote for candidate X. This is the sample proportion.
The population proportion is fixed but unknown, and the sample proportion is known but based on a random sample and hence the sample proportion is considered random. Also, anything computed using using the sample proportion is random as well. Therefore the confidence interval is random as well.
If Obama's sample proportion is 51 with a margin of error (based on 95% confidence) is 3.5, the confidence interval is 47.5 to 54.5. Does this mean that there is a 95% chance that the true population proportion is between 47.5 and 54.5? No! No no no. The true population proportion is fixed -- there's no chance anything about it. It's your confidence interval that's got that random element, so the correct interpretation is that there's a 95% chance that the confidence interval you computed covers the true population proportion.
Think of it like a ring toss game, where the confidence interval is the ring and the true population proportion is the peg. You know that when you toss the ring, there's a 95% chance that it will go over the peg. Unfortunately you never know if the ring is actually over the peg since the population proportion is never known.
It's a subtle difference but it's really important when we're bombarded by so many poll numbers each day. It's not the true proportion that's jumping around (although we would expect it to gradually change over time) it's the sample proportions and their confidence intervals jumping around. It's not the world being erratic, it's us.
Bob Schieffer has the crankiness covered already.
... although not by name. Obama referenced the "palling around with terrorists" line which gave McCain the opening. If this were a boxing match, Obama just put down his guard and dared McCain to hit him.
is why I think I've avoided class reunions so far. Last August would have been my 20th as well, and I hope those people had fun.
On a related note, Propecia ROCKS!
I'm really interested in how this will evolve.
If this is a virtual world for Muslims that doesn't have the kind of oppressive religious oversight that most of the real Muslim world does, then participants may be able to experience the kind of freedom virtually that they cannot experience in real life. As people come to desire that kind of freedom, and if it is accessible throughout the world, what will happen to the Islamic religious establishment as a result?
Then I could come up with a snarky rearrangement of the letters.
And I don't understand the people who say this was photoshopped. Are you implying that McCain had a rally with eight shirtless guys in the background, and then someone decided to write "Maverick" on their chests using Photoshop? Because that would be much much freakier...
Clearly if a person has not been taught to think critically then they can't wade their way through Republican scaremongering and lies. I don't believe that being overweight has any affect on critical thinking, but any factor that does could certainly affect politics in the future.
In my understanding, WIC checks and EBT cards are not on a set schedule, so if there are spikes of baby food sales at the end of the month and mid-month, these sales are not necessarily linked to WIC. It should be noted that Wal-mart, along with other food chains, keep meticulous records of WIC purchases. If they want to separate WIC from non-WIC purchases in their analyses they should have no problem doing so.
but at my local "World Market" (which is 80% Asian foods) the produce is almost always cheaper than at the regular grocery stores. And not just the more exotic foods -- apples and oranges are usually 30% to 50% less than the chains.
And frankly taking a trip to the local Asian market is worth it just for the Nong Shim Brand of Kimchi Ramen. It's ramen that rocks.
Were these four examples ALL the cases in which a black candidate ran against a white candidate? If so, then your thesis should be looked at seriously. If not and you chose them to prove your point, then there's no reason to take your position seriously because you didn't choose a representative sample to test your hypothesis.
the birth of a whole new sexual fetish. There's absolutely no doubt that such photos will end up online.
According to statistical theory, whoever has the higher number is probably in the lead. Being within the margin of error only means that it doesn't satisfy the 95% confidence criteria everyone uses as a default. So in that Rasmussen poll where McCain is up by 5 points, and 5 points is within the margin of error, we cannot be 95% confident that McCain is leading. However, if the margin of error were recomputed, maybe we could be 93% confident that McCain is leading.
There's a lot of peril in treating within/outside the margin of error as an on/off switch, and it can lead to major self delusion. And nobody needs self delusion.
The guy is getting progressively wackier...
If our paperwork or bag-tags got soaked, the Uniball ink never ran. They are very good pens. Getting out Sharpie ink is easy compared to getting out Uniball ink.
is that Harold's Chicken Shack will become a nationwide institution.
Chicken served from behind bullet-proof glass just tastes better...
I'm sorry to see you go and see Machinist go on hiatus. Best of luck in future endeavors!
The longer that those freaks are around the longer it will take the GOP to figure out how to fix their problems. Go Rush! Go Skeletor!
Much of the initial coverage about Fort Hood turned out to be wrong. Is there anything wrong with that?
The accountability imposed by another country for the CIA's kidnapping and torture reveals much about our own.
Fox News' morning show plays to type, talking about whether Muslims in the Army should face "special debriefings"
The survivor and author is upset about comparisons some on the right are making to genocide
219 Democrats and one Republican join in favor of the legislation, which passed by a narrow margin
Salon headlines in your mailbox
