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Another Poll
Topic Started: May 21 2004, 10:15 PM (243 Views)
somerled
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Admiral MacDonald RN
Since you guys are keen on polls.

Aussies want troops out of Iraq

Well, concidering we should have gone into Iraq in the first place.
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Sgt. Jaggs
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How about a Voyager Movie
somerled
May 21 2004, 10:15 PM
Since you guys are keen on polls.

Aussies want troops out of Iraq

Well, concidering we should have gone into Iraq in the first place.

Fifty-five per cent of those surveyed said should stay until the job was done, down two percentage points since the last poll just a week ago.


What, is 55% not a majority in Australia? Damn it Somerled, at least be an accurate malcontent! :frust:
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doctortobe
Speak softly, and carry a 57 megaton stick!
You do realize that the margin of error could make it go either way when the results are this close.
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Sgt. Jaggs
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How about a Voyager Movie
Margin smargin we are talking about majority here.
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doctortobe
Speak softly, and carry a 57 megaton stick!
I was talking about the first poll about the 47% wanting them to come home and 50% wanting to stay. Even with a 1.5% margin of error, it could be 50-50. I would also say that the title is misleading. A 50-50 split does not mean that the Australians want their troops home, it means that they are split on the issue. I could just as easily say that the results mean that Australians want their troops to stay.
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somerled
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Admiral MacDonald RN
You guys have missed the point -
Quote:
 
The Morgan poll of 533 people
, is supposed to be representative of 20M Australians - BS !

It is at best a very rough indication as the sample size used is far from statistically valid.

But I guess this point was a bit to abstract for the average SisterTrekker.
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doctortobe
Speak softly, and carry a 57 megaton stick!
I wasn't sure about the population of Australia. The polling for Iraq was 2000. Given that Australia's main inhabitation is along the coastlines and the fact that I did not have the time to compare the two populations, I did not bother to bring it up when I noticed the sampling.
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Admiralbill_gomec
UberAdmiral
So what?

Come on Sparky, you CLAIM to understand statistics. 533 people would be a margin of error of what... 4 percent? Stop WHINING.

Also, I doubt there are 20 million ADULTS in Australia. Hell, there are more people in Texas than in Australia.
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somerled
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Admiral MacDonald RN
Here's an applet that calculates confidence intervals (for NORMAL DISTRIBUTIONS).
Sample Size and Confidence Interval Calculator

The assumption is a NORMAL DISTRIBUTION for the population. This is actually rarely the case.

For your benefit - using the applet 533 out of 20000000 is +/- 5.6 % which is very rough !

Say 3/4 of these 20M are over 18yrs old , it is still +/- 5.5 %.


And if you want talk 300M yanks - 2000 samples , that's +/- 3% assuming a normal bell curve.

For those of you with a more mathematical bent - I recommend StatSoft Power Analysis Tools - I've used this in experimental designs and it is about as good a tool as you can get.
Quote:
 
How the "level of statistical significance" is calculated.
Let us assume that we have already calculated a measure of a relation between two variables (as explained above). The next question is "how significant is this relation?" For example, is 40% of the explained variance between the two variables enough to consider the relation significant?
The answer is "it depends." Specifically, the significance depends mostly on the sample size. As explained before, in very large samples, even very small relations between variables will be significant, whereas in very small samples even very large relations cannot be considered reliable (significant). Thus, in order to determine the level of statistical significance, we need a function that represents the relationship between "magnitude" and "significance" of relations between two variables, depending on the sample size. The function we need would tell us exactly "how likely it is to obtain a relation of a given magnitude (or larger) from a sample of a given size, assuming that there is no such relation between those variables in the population."
In other words, that function would give us the significance (p) level, and it would tell us the probability of error involved in rejecting the idea that the relation in question does not exist in the population.
This "alternative" hypothesis (that there is no relation in the population) is usually called the null hypothesis. It would be ideal if the probability function was linear, and for example, only had different slopes for different sample sizes. Unfortunately, the function is more complex, and is not always exactly the same; however, in most cases we know its shape and can use it to determine the significance levels for our findings in samples of a particular size. Most of those functions are related to a general type of function which is called normal. To index 


Why the "Normal distribution" is important. The "Normal distribution" is important because in most cases, it well approximates the function that was introduced in the previous paragraph (for a detailed illustration, see Are all test statistics normally distributed?).
The distribution of many test statistics is normal or follows some form that can be derived from the normal distribution. In this sense, philosophically speaking, the Normal distribution represents one of the empirically verified elementary "truths about the general nature of reality," and its status can be compared to the one of fundamental laws of natural sciences. The exact shape of the normal distribution (the characteristic "bell curve") is defined by a function which has only two parameters: mean and standard deviation

Posted Image illustrates the effect nicely.

Other types of distribution
Posted Image F

Posted Image Chi^2

are just two commonly encountered distrubutions other than binomial and normal distributions that are possible.

This is the effect of the confidence interval on expectation
Posted Image
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Sgt. Jaggs
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How about a Voyager Movie
^^^^^^^:lol: aaHHHAhA. The slide rule has come out! I love it! All this and you probably don't even like technobabble in your Trek! :lol:
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ANOVA
Vice Admiral
Come on JS:

It's his first semester taking stats. How's he supposed to learn the stuff if never gets to apply it?

I mean, look at what he's doing to pass the class.
1) Buying Statistics for Dummies
2) Visiting every statistics web page on the internet.
3) Appying what he's learned on the SisterTrek site, a site known for its statistitions.

Somerled:
How do you get a normal distribution out of a poll. The person is: for it, against it, or undecided. Three possible outcomes. Whats the null hypothesis for your test of significance?Don't force me to review my statistics books. When are you going to answer my claims on the "only path to democracy in Iraq"? You claimed it was "rubbish". Now acknowledge my counter.

ANOVA

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8247
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Apparently we look like this now
So, based on a percentage of apples, divided by the square root of the number of navel oranges, we get the absolutely correct number of people who are against tomatoes. :loling:
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Fesarius
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Admiral
^^^
Your math is somewhat faulty, but those are essentially the facts. :) ;)
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doctortobe
Speak softly, and carry a 57 megaton stick!
So somerland, can I take all my biological and military knowledge, use it in a post, and then when you don't get the point I was making that would require education into that specialized field of knowledge, rub it in your face then proceed to show off what I know about it?
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somerled
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Admiral MacDonald RN
Excuse me - but a kids in high school (at least here in Australia they are) are taught about students' T tests, normality, binomial and seven skewed probability distributions. There is nothing specialised about that basic stuff.

As to more advanced statistics - it's part of the core of many disciplimes including physics, engineering, chemistry, and from I have been told (by friends of mine studying medicine - or who have become medical doctors) of medical science.
If you personally don't have it then you'll be hard pressed to understand much of the literature in your own field.

Statistical reasoning is also very important in all manner of industries, and even labourers are expected to master the basics and also relevent advanced concepts.I know this because I have trained these types of workers in basic statistics.

If you don't follow or understand statistics - that's your problem and not mine , and you should go and learn something about it. I am firm believer that if you have knowledge - use it , otherwize why bother going to the trouble to acquire it in the first place.

PS : I don't have , or ever have owned Statistics For Dummys, I was being sarcastic when I used that title. I do however have in my library a few books on statistics that I regularly use.
ie
Using Multivariate Statistics - Barbara G. Tabachnick, Linda S. Fidell
Spss Advanced Statistics - Samuel B. Green, et al
Schaum's Outline of The Theory of and Problems in Statistics - by our old friend Murray Speigal
Statistical Process Control & Thinking Statistically Course notes by WESTAT and NEWSTAT
and naturally
Perry's Chemical Engineers' Handbook which also has this stuff covered.
Schaums Outline on Multivariable Statistics - I think it's out of print now.
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