Yes, they did and what I said is statistically correct. Figures don't lie but liars figure.
a 5% random sample is needed for a poll to be statistically meaningful. The pollsters try to get around that by saying their sample is not random but proportionally represents every faction in the total population. For example if 1% of the population is gay males who support the right to life then they must have 1 of them in every hundred sampled, and so forth for every possible faction in the country. Its foolishness, but you are free to buy into it if you want to.
It's an odd assertion to make, given that corporations spend billions of dollars a year using similar sampling methodologies to understand the consumer market. Why would corporations and pollsters spend all that money if it's worthless?
pinqy ,
Statistikhengst Darkwind
I'm almost certain that you aren't correct, so I've called in an economist and a few who know a bit about polls.
This is the math that I remember from statistics
The
estimator of a
proportion is
, where
X is the number of 'positive' observations (e.g. the number of people out of the
n sampled people who are at least 65 years old). ...
For sufficiently large
n, the distribution of
will be closely approximated by a
normal distribution.
[2] Using this approximation, it can be shown that around 95% of this distribution's probability lies within 2 standard deviations of the mean. Using the
Wald method for the binomial distribution, an interval of the form
will form a 95% confidence interval for the true proportion. If this interval needs to be no more than
W units wide, the equation
can be solved for
n, yielding
[3][4] n = 4/
W2 = 1/
B2 where
B is the error bound on the estimate, i.e., the estimate is usually given as
within ± B. So, for
B = 10% one requires
n = 100, for
B = 5% one needs
n = 400, for
B = 3% the requirement approximates to n = 1000, while for
B = 1% a sample size of
n = 10000 is required. T
hese numbers are quoted often in news reports of opinion polls and other
sample surveys.
Sample size determination - Wikipedia, the free encyclopedia
Also
How many people are there in the group your sample represents? This may be the number of people in a city you are studying, the number of people who buy new cars, etc. Often you may not know the exact population size. This is not a problem. The mathematics of probability proves the size of the population is irrelevant unless the size of the sample exceeds a few percent of the total population you are examining. This means that a sample of 500 people is equally useful in examining the opinions of a state of 15,000,000 as it would a city of 100,000. For this reason, The Survey System ignores the population size when it is "large" or unknown. Population size is only likely to be a factor when you work with a relatively small and known group of people (e.g., the members of an association).
The confidence interval calculations assume you have a genuine random sample of the relevant population. If your sample is not truly random, you cannot rely on the intervals. Non-random samples usually result from some flaw in the sampling procedure. An example of such a flaw is to only call people during the day and miss almost everyone who works. For most purposes, the non-working population cannot be assumed to accurately represent the entire (working and non-working) population.
Sample Size Calculator - Confidence Level, Confidence Interval, Sample Size, Population Size, Relevant Population - Creative Research Systems