Distinguish sample from population.?
957375
Sample means you only obtain a part of the data.  Population means you obtain all of it.  When calculating sample standard deviation you divide by one less that the number in your sample; population S.D., divide by the full number in the population.
488365
Try again Paul C.  The population doesn't need to look normal.\n\nThis all comes down to the Central Limit Theorem.  Let's assume that I take many samples of size 1004 from the population.  Well, each sample will have a percentage that is different from the population percent, because samples are going to look different from the population.  Also, each sample is going to look different from each other, because they are different samples.  If we were to draw a graph that looked at the "behavior" of these many samples, we would notice the following:\n\n1.  If I were to average out all of these sample percents, I would get the population percent.  Hopefully you can see why this would happen.  Sample percents will be around the population percent, but just be off by a little bit.\n\n2.  If I were to look at the spread of the percents, the spread would be smaller as bigger samples were taken.  In other words, if I had taken samples of size 500, the sample percents would be more spread out than for samples of size 1004.  That is because if were take larger samples, then we have more information about the population, so we should expect to get closer to the population percent.\n\n3.  As I take larger and larger samples, the shape of the graph of sample percents would look more and more like a normal curve.  A normal curve is shaped like a bell, where the middle of the bell is were the population percent is.\n\nSo Paul C, it doesn't matter that the population doen't look normal; all we need is a sample that is large enough.\n\nNow the margin of error on polls is typically going to be\n\n2*sqrt(p(1-p)/n))*100%\n\nwhere p is the sample proportion (the sample percent divided by 100%) and n is the sample size.  It can be shown that this margin of error would be at its largest if p = 0.5, so the largest the margin of error would be in this case would be\n\n2*sqrt(0.5*0.5/1004)*100% = 3.2%\n\nThis is typically associated with 95% confidence.  This basically means that if I were again to take many, many samples of size 1004,  95% of the sample percents would be within a margin of error away from the true population percent.\n\nThis of course depends on the sample that is taken.  The online polls that you see would not be good estimates for the population percent.  Below I have a link to a story that MSNBC has on each of its online polls.  The title is "How 1,000 people can be more representative than 200,000."  I think that it is a very good explaination of this topic.
808395
You can't apply statistics (to anything) unless you have a sufficient number of values to work with.  For example, if you took a poll of who people were going to vote for, if you only asked 5 people, you might not get an accurate representation - but if you ask 5000 then the margin of error gets smaller.  With molecules, there are millions of them.
324717
what type of statistics?
852941
How theoretical is it- can you type in a sample problem?
889887
try the census. you may find something there.
181649
what statistical informations can be extracted from difference between actual and estimate data?and how?
124804
For an uncertainty x of 0.01 (which your 99% accuracy would be) you need 1/x^2 samples which would be 10000.  This is true for a large population (>>10000).  I believe you still need that many for 20000 population but am only 99% sure.\nSource: Best recollection of a stat course 50 years ago.
487348
The mean of the average of 100 randomly selected travelers would just be the same as the population mean, which is 190.\n\nThe SD of the avereage of 100 randomly selected travelers would be the SD of the population divided by the square root of the sample size, which is 20/sqrt(100) = 2.
795974
the sample would be ....for example: if you used a group of 30 women between that ranged from18-22yrs...the sample mean would be women of the age 20.
835888
Basing this on rough statistics you'd be looking at a maximum current population of about 60 million, give or take a million.  That is of course assuming that all other aspects remain the same.
1147020
to determine the ideal sample size for a population, slovin's formula is used which is\n\nn = N / ( 1 + (N*e^2))\n\nWhere:\nn = number of samples\nN = total population\ne = margin of error\n\nSample Calculation:\nA group of students want to know the age of students in a high school but do not have the resources to survey an entire population of 2,500. If they want to use a sample with a 5% margin of error, what should their sample size be?\n\nGiven:\nN = 2,500\ne = 5% = 0.05\n\nRequired: n = ?\n\nSolution:\n\nn = N / ( 1 + (N*e^2))\nn = 2500 / ( 1 + (2500*.05^2))\nn = 2500 / 7.25\nn = 344.83   ~ 355
896151
To answer your question, i need to give u an example.\nConsider all real integers from 1 to 10. Let this be our population. \nNow i draw a sample, let this sample be x\nx ={ 3, 4, 5, 6}\nto find population mean, divide the sum of (all integers from 1 to 10) by 10. This will give you 5.4\nnow our population mean is = 5.4\nConsider the sample x now.\nexpectation is the mean of a sample.\nE(X) = (3 + 4 + 5 + 6)/4 = 4.5\nNow, if you take a larger sample (y)\ny = { 2, 3, 4, 5, 6, 7, 8, 9}\nE(Y) = (2 + 3 + 4 + 5 + 6 + 7 + 8 + 9)/8 = 5.5\ncompare this with the population mean, which is 5.4.\nTherefore, if you take a sample of N distinct numbers, where N <10,\n"the expectation of the sample will converge to the population mean as N approaches 10." - this is how the population mean and the expectation of a sample are related.
579180
if you're talking about in statistics, a convenience sample would be asking the first 100 people who walk past you on the street the same question. it tends to create biased results.
38864
You can find that sort of information on a government demographics webpage.  Just google it.
824058
Population density is a measurement of population per unit area or unit volume. It is frequently applied to living organisms, humans in particular.\n\nyou may want to check this site:\nhttp://en.wikipedia.org/wiki/Population_density\n\nsite also contains methods for measuring population density
834182
sample space=8\nnumber of outcomes with at\nleast 2 heads=4\n\nP(at least 2 heads)=4/8=1/2\n\nodds:even money\n\ni hope that this helps