Talk:Secular variation

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Untitled[edit]

The phrase "secular variation" is not a suitable term for an encyclopedia article.

I disagree. I'm not able to expand this because I don't really know time series, but I have no doubt that this could be expanded far beyond a dictionary definition, and I expect anyone who realizes that time series has been an area of active research for many decades would agree with me. Michael Hardy 20:20, 22 February 2007 (UTC)[reply]

Well, I don't want to argue with you, Michael. If you want to delete the "PROD" tag, go ahead. I'll just leave the article alone if you do that. I do have about 20 years' experience with time series data, and in fact I often worked to eliminate the secular trend from a time series, so that I could model the residuals better. But I would put a description of such techniques under "spectral analysis", or "regression analysis", or some heading like that for the purposes of an encyclopedia. The "secular variation" is often just the straight line that best fits (by least squares) the time series data, and the residuals from that regression sometimes show some sort of periodic or quasi-periodic behavior. DavidCBryant 21:25, 22 February 2007 (UTC)[reply]

I thought about this a little longer, and you might be right, Michael. They say that familiarity breeds contempt. Maybe I got so used to thinking of a secular trend as a triviality (when I worked with that sort of data) that I can't really be objective now. I mean, the really interesting part of many time series is what's left over after any secular trend has been eliminated. So that's what I think is important. I guess it might not look like that to somebody else. Weird, eh? DavidCBryant 21:44, 22 February 2007 (UTC)[reply]

Asymptotic Analysis[edit]

The phrase 'secular term' also appears in asymptotic analysis of many ODEs (cf. the Van der Pol Oscillator, Mathieu's Equation) and appears to mean 'a term which is growing due to resonance (and would therefore break the asymptoticness of the approximation)'. I would like to learn more, but this article seems unhelpful and not geared towards a continuum mechanist. However, this is indeed a topic of interest. 82.16.99.131 (talk) 13:44, 21 October 2008 (UTC)[reply]

The secular variation of a time series is its long-term non-periodic variation[edit]

I don't think this is even true. SV is long-term trending. Something varying chaotically within a limited domain would not be considered secular William M. Connolley (talk) 08:00, 17 July 2011 (UTC)[reply]

I can't speak for other fields, but in geomagnetism the term is applied to chaotic variations. RockMagnetist (talk) 10:29, 17 July 2011 (UTC)[reply]

Odd. can you give an example of the term being used? William M. Connolley (talk) 11:03, 17 July 2011 (UTC)[reply]

See Geomagnetic secular variation and its links. RockMagnetist (talk) 19:05, 17 July 2011 (UTC)[reply]

That doesn't really help. On that page, it is used as a synonym for "variations longer than a year", which is yet a different meaning. Is that really what you use it to mean? William M. Connolley (talk) 20:41, 17 July 2011 (UTC)[reply]

Yes. It isn't my definition - it comes from the books that I cite. If it seems a little lacking in rigor, remember that geomagnetic field variations are (probably) chaotic and have variation on all time scales. RockMagnetist (talk) 21:23, 17 July 2011 (UTC)[reply]

I think you're right that, in other subjects, it refers to a trend, and I think that is probably the original definition of secular variation. However, the paleomagnetic definition can't be ignored because it is probably the only subject in which secular variation gets its own chapter in textbooks. RockMagnetist (talk) 21:32, 17 July 2011 (UTC)[reply]

Citations for Biological Anthropology section[edit]

The citations I've found and provided back up that a secular trend has been observed in menarche (and many others exist, but I figured the ones I provided should be sufficient), however I'm sure that I've cited them the wrong way. I used the Wikipedia:Citation templates for in-text citations, but am not entirely sure the right way to provide the footnote format of citations that the rest of the article has. My apologies for the inconsistent formatting. Would anyone who knows how to do footnote citations be able to modify those? Bush6984 (talk) 22:47, 3 December 2014 (UTC)[reply]

I fixed it for you. You had it mostly right - to make the citations inline, just surround them with <ref> ... </ref> tags. However, there is another issue that needs to be addressed. All the cited sources are primary - peer-reviewed research publications. It would be better to use a single secondary source (such as a review article or book), if it can be found. See SECONDARY for more information. RockMagnetist(talk) 00:16, 4 December 2014 (UTC)[reply]

Origin / Etymology[edit]

Please explain the origin of the term, and how/whether it relates to the everyday meaning of "secular" (i.e. not religious). —DIV (120.18.190.20 (talk) 13:39, 16 October 2018 (UTC))[reply]

I added a section on etymology. RockMagnetist(talk) 16:27, 16 October 2018 (UTC)[reply]

Good job :-) —DIV (120.18.176.244 (talk) 22:23, 24 October 2018 (UTC))[reply]