Talk:Sample size
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[edit] Maximum Error
I see someone has changed the inequalities around again - the reason they were set the way that they were is that if we want a certain maximum error epsilon, then we require the half-width of the CI to be at most epsilon i.e. B<= epsilon. Therefore we will obtain a minimum, (rather than a maximum) sample size required (which the inequalities would suggest in their current state). I can see no interpretation which would lead us to set these inequalities the other way around, particularly that would give us a maximum value of n, rather than a minimum! HyDeckar 00:48, 22 March 2007 (UTC)
- Look, I'm really quite confident about this - if anyone feels like responding, I'm more than willing to figure out what is right, but I'll change it for now (but come back at me here rather than start a possible 'edit war') HyDeckar 14:22, 23 March 2007 (UTC)
[edit] Question
I am unsure about the statement
Note, if the mean is to be estimated using P parameters that must first be estimated themselves from the same sample, then sample size should be n+P.
If we mean to increase the sample size by P so as to maintain enough degrees of freedom, then we would arguably need to consider the use of degrees of freedom throughout, i.e. t distn's etc... Also, such a situation would typically involve covariates, which may allow us greater accuracy than the CI given here. Given all of this, I'm just not sure that this comment is a useful one to have here.
- An article on sample size is a good place to introduce the concept of degrees of freedom. Suggest:
Note, if the mean is to be estimated using P parameters that must first be estimated themselves from the same sample, then to preserve sufficient "degrees of freedom" sample size should be at least n+P.
- Looks good HyDeckar 00:48, 22 March 2007 (UTC)
[edit] Old Stuff
Can someone please stop User:Lgallindo from vandalizing this page! I see he has problems with someone else vandalizing a page on sampling, but this has nothing to do with that. -- Mbhiii 18:23, 23 October 2006 (UTC)
[edit] New Version
New version now online HyDeckar 16:36, 20 March 2007 (UTC)
I have written a tentative new version of this page, it is available for comment on my user page. Unless I get a huge negative response, I'll load it up in a couple of days. HyDeckar 15:10, 19 March 2007 (UTC)
- It seems like a big improvement to me. I say go for it. -- Avenue 03:06, 20 March 2007 (UTC)
What you wrote is good with improved notation and generally, BUT you DELETED the useful "rule of thumb" and its derivation - a bad move on your part. I'm restoring it. --63.98.135.196 19:47, 20 March 2007 (UTC)
- Sorry about that, accidental 'friendly fire' - I've rehashed the "rule of thumb" (not under that name) to line up with the rest of the article stylewise. HyDeckar 08:28, 21 March 2007 (UTC)
[edit] Clarification
This article is crazy-confusing. Piuro 22:17, 23 October 2006 (UTC)
Please do not remove the confusing tag until the article is much clearer. Piuro 19:12, 24 October 2006 (UTC)
Hi, I hope this works. The main ideas I'm trying to answer are (1)just what does "sample size" mean, (2)what are its effects, and (3)how can you estimate it? I think the first paragraph answers (1), the first and second answer (2), and the third and fourth answer (3). --Mbhiii 16:23, 25 October 2006 (UTC)
Hello Khatru2, thanks for bolding "Sample size", but you should know I wrote every word of Sample size and take responsibility for it. That's what my (or anyone else's) signature means, so please leave it. It provides a quick link to my contact information for further, detailed or ancillary discussion. --Mbhiii 12:40, 26 October 2006 (UTC)
Whoops, as per Wikipedia:Ownership of articles, no signature. --Mbhiii 17:16, 26 October 2006 (UTC)
[edit] Notation
There is a misconception that the sample size is denoted N, but all serious sampling texts (e.g. Cochran, or Sarndal et al) use n for the sample size and N for the population size. I accordingly changed N to n throughout the article. However 68.221.1.30 (talk) changed it back to N. I see this as a very retrograde step, which is likely to confuse our readers. It was only slightly mitigated by the addition of an end note that N usually denotes the population size. Another note was added to say that N is being used for legibility.
Why should we use the wrong notation? Legibility is not a good reason; lower case italics are the symbols used most often in mathematics, so anyone who will understand the formulae should be very used to reading this sort of text. A note saying that we are doing this intentionally does not solve the problem; it just makes us look foolish rather than ignorant. -- Avenue 01:06, 4 February 2007 (UTC)
- I'll leave it. My eyes are old, so legibility is a top priority. It'd be nice if someone made the small n larger. --mbhiii 15:16, 14 March 2007 (UTC)
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- Did you know that you can increase the size of displayed text in most browsers by pressing the Control and "+" keys simultaneously? (See the links at Computer_accessibility#Web_browser_accessibility_features for a lot more information.) While I agree it's important to keep accessibility in mind, I don't think changing the size of individual elements such as the small n is a good idea. -- Avenue 21:58, 14 March 2007 (UTC)
