Talk:Power law

message: I propose that our revised power law article become the redirect point for Fat tail and Heavy-tailed distribution. I've placed such a suggestion on the talk pages of each of these articles (which substantially overlap with the revised power law article, and with each other).
Paresnah 20:14, 13 March 2007 (UTC)
replies: text: Also, the Extreme value theory article, which mentions 'tail-fitting' but points to a non-existent article on the topic, should be connected to the Power laws subsection on estimating the tail exponent of power-law distributions. Paresnah 20:21, 13 March 2007 (UTC)
replies: text:  This latter point (linking with extreme value theory) is now done. Paresnah 01:28, 17 March 2007 (UTC)
thread_title:  Merging with other articles 

message: I concurr with the removal of the two references on terrorism; if the article isn't going to list all the citations that show power laws in weird systems, then it shouldn't privilege a few while ignoring others. So long as we keep the links to major review articles like Newman's up-to-date, we can let the academics keep track of which systems show power laws -- Paresnah 23:38, 28 August 2006 (UTC)
thread_title:  References to terrorism 

message: Should it be y=axk, where a is a constant? -- Heron
:Yes, I believe so, since Zipf's law is a power law and has a probability distribution of the form of y = ax-b. -- Lexor 22:37, 18 Aug 2003 (UTC)
replies: text: A more general relationship would be y \sim x^{k} (i.e. y "goes like" x^{k}) rather than assuming a literal equation like the above.  e.g. consider the equation y = (x - a)^{k} where a is constant. WebDrake 22:31, 7 October 2005 (UTC)
thread_title:  (Comments 2003-2005) 

message: I have deleted some external links that were unrelated to this subject and could not be considered external sources of information on power laws. There are lots of published and unpublished scientific works that can be related in some way to the application of power-law techniques, but do not apport any knowledge to the generic properties of power laws or generic applications and methods.
20:31, 21 February 2006 (UTC)
replies: text: Sorry but I don't agree with 161.116.80.71 about this.  Why does the Wikipedia article have to discuss only generic properties?  Referring readers of the article to a variety of sources which illustrate the diversity of cases in which power laws occur seems helpful and constructive to me.  -- JimR 03:06, 26 February 2006 (UTC)
thread_title:  external links 

message: This article, the Zipf's Law article, and the Pareto distribution article have significant overlap, for obvious reasons. Is it worth trying to create a central article for this set of material? --Experiment123 02:38, 8 March 2006 (UTC)
replies: text: I don't think so. Zipf's Law is a particular case from linguistics, and Power laws are not exclusively statistical, but also found in natural sciences. By the way, there is also overlap or a common theme with e.g. 80-20 rule, Lorenz curve and The long tail.--Niels Ø 18:57, 8 March 2006 (UTC)

text: I re-read the above, and yes, I do actually think a central article clarifying the relationship between these various topics would be good, but no, I don't think the articles should be merged. In fact, a while ago I created an article listing these articles, and linked each article to the list instead of to all the other articles. I never found a good name for my list, though, and it was afd'ed.--Niels Ø 09:49, 9 March 2006 (UTC)
replies: text:  Yes, that's the way I was thinking, too: relatively brief articles for Zipf's Law, Power Law, Pareto, etc., which all contain links to a meatier piece that can discussed shared concepts and talk about the relationships between the subjects. I see what you mean about the name, though. "Power Law Distributions" maybe? Do you have your old article around still somewhere?  --Experiment123 12:34, 9 March 2006 (UTC)
replies: text: It never was a proper article; it was just a list of links to the articles in question. Unfortunately not competent to write such an article, but I'd love to read it! - By the way, add 10/90 gap to the list.--Niels Ø 10:18, 12 March 2006 (UTC)
thread_title:  Merging Zipf, Power Law, and Pareto? 

message: The article refers to Mandelbrot and Taleb as "recently" popularising the presence of power laws in financial markets.  Actually Mandelbrot's statistical analysis of price fluctuations, showing power law tails ("fat tails"), dates back to---and was well-known in---the 1960s.  There's also the Pareto law for the distribution of income, which is another fat tail distribution.
More generally the article needs to be more clear about distributions/scalings which are power law for only part of the range.
I don't have time to make the change now but will try to add some material in the near future. —WebDrake 09:57, 29 April 2006 (UTC)
thread_title:  Financial market power laws 

message: I'm pretty sure the Weibull distribution is not an example of a power-law distribution, as the current article claims.  When Weibull parameter k=1, it's the same as the exponential distribution, which is definitely not power-law.  I'm fairly certain that Weibull isn't power-law regardless of the value of k, but in case my understanding is muddled, I wanted to give others a chance to comment. —The preceding unsigned comment was added by Agthorr (talk • contribs) 14 June 2006.
: Agreed: it is not a power law (although the formula for the failure or hazard rate h(x;k,\lambda) given in the Weibull distribution article is a power law).  I've removed the Weibull distribtuion from the examples, and put it in See also instead.  -- JimR 05:31, 18 June 2006 (UTC)
thread_title:  Weibull not power-law? 

message: I have added "with k > 1", as, e.g., with k = 1 dX/dt = aX^k describes just an exponential, with k = 0 we have a lineal function and so on.  —The preceding unsigned comment was added by Athkalani (talk • contribs) 2006-07-13.
: Sorry but I don't think this is correct.  There are significant cases where k<0, for example, inverse-square laws and critical exponents.  The cases k=1 (not exponential but simple proportionality) and k=0 (a constant function) are not very interesting, but they are still degenerate cases of power laws.    I've reverted this change.  -- JimR 04:24, 15 July 2006 (UTC)
replies: text:  Athkalani appears to have confused the equation y = ax^k with the equation dx/dt = ax^k.  It's not an issue. —WebDrake 21:59, 15 July 2006 (UTC)
thread_title:  with ''k'' > 1 

message: I've removed the comment that "It remains to be seen whether knowing that something follows a power law has a practical use".  This seems to me just the sort of very silly POV thing said by people who are cynical about the whole complex-systems-science field.  Knowing that something is power-law distributed is as practically useful as any other accurate description of nature.  ---WebDrake 10:54, 13 July 2006 (UTC)
replies: text: It does seem surprising.  But there were already two external links in the article justifying the mention of war and terrorism.  I've turned these into explicit reference notes to make the connection clear.  -- JimR 05:07, 30 July 2006 (UTC)
replies: text:  I think this is a style issue.  The article jumps too quickly into "where power laws are observed" rather than telling you what they are first.  As for the juxtaposition of "war and terrorism" versus sciences, power laws really are very ubiquitous — they are observed in hard sciences, biology, social sciences, the works.  It would be better to make a short comment ("found in many situations in nature") initially and elaborate later: the trouble with making a list is that everyone and their mother wants to add their personal pet example (it's happening on the self-organized criticality page too).  Will try to rewrite soon. —WebDrake 19:37, 3 August 2006 (UTC)
thread_title:  "Practical use" 

message: What's the justification for power laws being in the "exponentials" category?  —WebDrake 09:30, 19 July 2006 (UTC)
thread_title:  Category: exponentials 

message: Following a couple of brief exchanges between Paresnah and I on our talk pages, it's perhaps best to continue the debate here.  The discussion is on how to phrase comments relating to universality.
Anyway, here's what Paresnah wrote:
:I think that the section on universality needs to make a couple of things explicit. In some systems in physics, e.g., spin glasses, the universality of power-law behavior rests on firm empirical and theoretical grounds. For other systems, such as complex networks or various sociophysics applications, claims of universality seem to be mere speculation. It seems to me that a lot of statistical physicists who work in these areas have imported the familiar (to them) idea of universality, but are applying it in a way that may not be congruent with its original meaning. For instance, in statistical physics, critical exponents describe the functional behavior of a variable, while in these "complex systems", the exponent of a power law describes the probabilistic behavior of the variable. Even if we accept that the idea of universality is applicable to probability distributions, significant problems remain.
:For instance, universality requires the coincidence of the scaling exponents. But, in most of these "complex systems", the estimates of the scaling exponent's value are extremely coarse (this is at least partially due to the MLEs not being widely used). People often claim universality after seeing a power law with an exponent in the range 2 < \alpha < 3, rather than by precisely matching exponents as was done for the more traditonal physics systems. Also, 2 < \alpha < 3 is a huge range over which to claim a precise matching, and it's expecting a lot to assume that, as the fitting methods improve, the values will continue to match in a precise way among these disparate systems. And, there are a large number of stochastic mechanisms that all produce power law distributions with exponents in exactly the observed range, so there doesn't seem to be any reason that we should a priori expect any universality class, in the traditional sense, to apply to these probabilistic systems (more on this in a moment). One of the silliest claims of universality in a "complex system" is in the "scale-free networks" literature, concerning the structure of the Internet. Walter Willinger, David Alderson and their colleagues have criticized this claim extensively in a series of careful articles, such as this one. 
:Finally, there are no validated theories that describe why we should expect to see power laws with certain exponents in these "complex systems". There are lots of interesting ideas, but researchers rarely do the necessary work to validate their models. Without such validation, it seems hazardous to try to generalize two systems into a universality class. Rather, similar behavior could just be a coincidence - perhaps two different mechanisms just happen to produce power law distributions with the similar exponents, but, for other reason, there is no way to put them in the same class of systems. (Or, similar behavior could be a data artifact.) Renormalization provided this deeper connection for many traditional systems, but there is not yet such a theory for any "complex systems". (At least, I'm not aware of one...)  Michael Mitzenmacher has commented on some of these issues in a recent editorical for Internet Mathematics (available from his publications page). The problem is basically that people have been getting ahead of themselves (and what their data supports) in pushing into these new "complex systems" areas. I'm pretty sure that all of these issues will get sorted out eventually, but since there's already a lot of confusion in the "complex systems" scientific literature, I think we need to be careful in the wikipedia article not to repeat things as fact that are merely speculation.
:Now... I wonder how we can work this perspective into the article.
I would reply that I think it depends on what you're looking at.  For example, in the case of self-organized criticality I don't see any reason to doubt that well-defined universality classes exist (and indeed a lot of work has been done here, although I don't think there is a complete theory at this point).
On the other hand as regards scale-free networks I can agree, there are various ways to tune exponents with these models and there is not really a coherent point of view yet.  Part of the problem may be that they are rather abstract and are not "physical" in a conventional sense.  But they can emerge from physical models (see e.g. the paper by Paczuski on the self-organized criticality page) which may help to resolve some issues in the future.
The issue of coarse-grained observation I think can be dealt with simply.  In some empirical cases exponents are not firmly established so it's difficult to make statements.  Some may not even be power laws!
That's a very brief reply that doesn't really do justice to your detailed comments, but I think we can deal with the issue quite simply: we refer to traditional thermodynamics and SOC, and then add some comments about "whether universality can be extended beyond these cases continues to be a matter of debate, and some have said ..."
I'll try to read more deeply on the papers you suggested (any more would also be welcome) and come up with some new text. —WebDrake 09:11, 12 September 2006 (UTC)
replies: text: Right, exactly. The problem here is, I think, that there are several different communities that all deal with power laws (and universality), and we need to be careful in the wikipedia article about the generality of its statements about them. That is, the article should probably note important differences between the meaning of power laws in different communities (e.g., functional versus probabilistic, or critical behavior versus other processes). In some places, such as SOC, the evidence of power laws and universality seems pretty clear (NB: I'm not an expect in SOC), while in others, like scale-free networks and terrorism, it's much less clear, and claims of universality are probably wrong (at least, I would say there's no a priori reason to believe them, and the empirical evidence seems poor). Paresnah 21:29, 12 September 2006 (UTC)
thread_title: Exponent/universality issues

message: As a layman I find this article very inaccessible. The top paragraphs do not explain at any point in plain english what power law is, it uses a mathematic sum to do the explaining. I'd rework it but I just dont understand what you are trying to explain. —The preceding unsigned comment was added by 210.49.213.27 (talk) 01:52, 16 February 2007 (UTC)
replies: text: I'll second that.  An example of the application might serve to illustrate what it is. Crag (talk) 18:20, 12 May 2008 (UTC)
thread_title:  Accessability 

message: a graph would be nice.  Puddytang 01:38, 16 May 2007 (UTC)
thread_title:  Pictures please! 

message: I question the use of the term "polynomial" in the intro. Polynomials have integer exponents, where in power laws, as I understand them, the exponent can be any real number. The fact that k need not be an integer should at least be made clear.--agr (talk) 14:00, 4 March 2008 (UTC)
replies: text: You are correct. I have edited the article to reflect the proper definition of polynomial, removing, for example, "Typically, power-law functions are polynomials in a single variable..." Harold f (talk) 10:59, 18 August 2013 (UTC)
thread_title:  Polynomial? 

message: The estimator attributed to Hall only applies to continuous data (not discrete), and this is not made very clear in the discussion ('real' is not necessarily 'continouous'). Also, there is discussion in the 'literature' about how this estimator does not work very well. I haven't been able to get it to work for me either.  —Preceding unsigned comment added by 136.177.20.13 (talk) 17:53, 10 February 2009 (UTC)
thread_title:  Estimating the exponent from empirical data 

message: This is given as an example of a power law, when, in fact (as the Wiki link even discusses), it is an exponential law.  —Preceding unsigned comment added by 136.177.20.13 (talk) 21:28, 10 February 2009 (UTC)
thread_title:  Gutenberg-Richter example 

message: please forgive me as i have never tried to ask a question or add to a discussion before.  i am also not a mathematician so forgive me if i am misunderstanding a technical concept.  however, in reading the introduction to this article, i came across the examples of "frequencies of family names" and "frequencies of words in most languages".  i have 2 question with regard these examples:
1.  while the example of the number of cities vs population size is clear, it is unclear (at least to me) what is the attribute of the family name or words that is being raised to a power to get the frequency?  is the relationship between the number of family names that share a frequency (e.g. only one name (brown, for example) has a frequency of a, while 10 different names have a common frequency of b such that they would be represented by points on the graph as 1 to the a and 10 to the b, or to some constant power 1 to the c, and 10 to the c)?  or is the name or word itself the "attribute"?  or does it have to do with the length of the name or word or the ordinal value of the placement of the letters in the alphabet?
2.  if the name or word itself is the "attribute", is it accurate to say that it is an example of the power law (rather than just something which mimics it) because you are not really raising the attribute of the name or word to any power to obtain it's frequency.  the frequency is merely distributed in a similar fashion.  one could not, for example, take a new family name or word ("xzerq", for example) and use the power law to calculate it's frequency.  if you cannot use the law to calculate the frequency, how can it be said to follow the law?
again, my apologies if this is a ridiculous question.  i just didn't understand or wasn't able to reconcile the examples with the explanation when i read it so i assumed other non-mathematicians might have the same problem.
CuriousAnton (talk) 16:58, 16 April 2010 (UTC)
thread_title:  clarification needed? 

message: It is written in the page that Student's t-distribution (continuous), of which the Cauchy distribution is a special case are Examples of power-law distributions. Is this true? phauly (talk) 13:14, 15 September 2010 (UTC)
thread_title:  Error? 

message: The editor who added the new section writes "I googled the names from memory and adapted one of the first results.  These terms are quite common in astrophysics.  I'm not sure which kind of source would be suitable though, so feel free to add whatever you find relevant.  Skippy le Grand Gourou (talk) 16:48, 24 September 2010 (UTC)
replies: text: Note that the power law with an exponential cutoff is already defined under Power law#Power-law distributions (without citation either…), so some merging or reorganization might be wise.  Skippy le Grand Gourou (talk) 20:31, 24 September 2010 (UTC)
thread_title:  Unsourced variants 

message: Clauset et al. show that their forest fire data can NOT reasonably match a power law. I'd like to see a mention of this recent backlash against the everything's-a-power-law-give-Per-Bak-a-Nobel-Prize trend.  —Preceding unsigned comment added by 38.103.165.36 (talk) 23:55, 11 November 2010 (UTC)
thread_title:  Power laws overused 

message: Recently the accuracy of several power law claims has been called into question. This is still an area of active research, and the results are unclear. This leads to several editors adding power law examples only to have others delete them due to controversy (real or not).  
To avoid confusion to those who may only want a broad overview, I propose creating a section on controversial power laws. This will inevitably make some people upset - "but my favorite power law is real/was accepted to a prestigious journal, etc."  However, in keeping with Wikipedia's goals of accessibility and accuracy, I think it's best to include only the clearest of examples, rather than mixing in the clear power laws with the contested ones.
I'd say an example/method is contested if there are reasonable published academic articles claiming for/against the power law status. If your favorite example falls into this category, tough, unless it's abundantly clear that the criticisms are false. The other option is to just ax all controversial claims entirely, but I don't think that's entirely fair. 
Finally, I think a bad criterion in this case would be to ask a single expert, since the experts still vehemently disagree on power laws in many fields, and egos, careers, and dollars are on the line. Octochimps (talk) 06:37, 6 July 2011 (UTC)
thread_title:  Controversy 

message: In its present form, the article is mainly about power law distributions. Scaling law redirects here, but simple scaling law relations are hardly explained, like weight being proportional to the cube of the size of animals. /Pieter Kuiper (talk) 08:13, 15 November 2012 (UTC)
thread_title:  Mainly about power law distributions 

message: How interesting: In the book "Multifractal Financial Markets - An Alternative Approach to Asset and Risk Management" written by Ms Yasmine Hayek Kobeissi (Springer, New York, 2013) we can read the following on page 8:
:"Power laws are interesting because of their scale invariance. That is, given a relation f(x) = ax^k, scaling the argument x by a constant factor c causes only a proportionate scaling of the function itself."
In the Wikipedia article it says:
:The main attribute of power laws that makes them interesting is their scale invariance. Given a relation f(x) = ax^k, scaling the argument x by a constant factor c causes only a proportionate scaling of the function itself. That is, f(c x) = a(c x)^k = c^k f(x) α f(x). That is, scaling by a constant c simply multiplies the original power-law relation by the constant c^k
There is no reference in the book to Wikipedia.
It might however also quite well be that the author actually inserted these lines herself into Wikipedia before using them also in the book. Especially if some author has studied a certain topic in depth, it is not so unlikely that he/she also has written about it in Wikipedia. And once a good wording is put together in one's mind to explain something, this can repeatedly appear in presentations, articles etc. 212.71.114.224 (talk) 11:49, 27 August 2013 (UTC)
replies: text: You are correct, the author of that book appears to have copied the text verbatim from Wikipedia. As to who first inserted that text, it can be searched for in the article edit history. 67.198.37.16 (talk) 17:57, 24 February 2020 (UTC)
thread_title:  Missing citations to this article in the book "Multifractal Financial Markets"? 

message: The article defines the symptotic exponent  as where p(x) is the density p(x) = Constant * x^\alpha rather than Constant * x^{-\alpha-1}. It is consistent but can be confusing as it is not customary in the literature. Limit-theorem (talk) 10:32, 1 December 2013 (UTC)
thread_title:  Definition of tail exponent different from literature

message: Wealth distribution in a paper about craters? Srsly? --2003:51:AF2C:3971:917C:A7BD:38A:EA1D (talk) 10:20, 20 April 2014 (UTC)
thread_title:  Reference "Neukum" probably wrong 

message: The section on empirical examples "introduces" s.  This is unclear, given the grammar of the sentence.  Is s crime type?  What is this paragraph trying to say in normal English?211.225.33.104 (talk) 04:46, 11 July 2014 (UTC)
thread_title:  s? 

message: The section entitled "No average" has question that isn't answered  [the billionaire enters the room, and the mean skyrockets; the median moves a smidgeon; so what?] and then veers from income to car exhaust.  211.225.33.104 (talk) 04:51, 11 July 2014 (UTC)
thread_title:  No average - little sense 

message: Someone mistook P(X>x) for p(x), i.e. survival function for density. For L(x) the slowly varying function to apply, one needs to correct. Also confusion between parameter \alpha and \alpha-1Limit-theorem (talk) 13:20, 25 August 2016 (UTC)
thread_title:  Mistakes in text 

message: I am adding the power law of CPU cache misses as an example in this article. It has been experimentally shown since the 1970s that the cache misses follow an exponential relationship with the size of the cache.Ysrajwad (talk) 14:12, 18 October 2016 (UTC)
replies: text: An exponential relationship is not a power law. Please explain. Limit-theorem (talk) 10:40, 19 October 2016 (UTC)
thread_title: Adding example of power law of CPU cache misses

message: The mathematical representation first encountered in the article defines the exponent as -k and the scaling factor as a. Unfortunately, the very next section (2.2) redefines the exponent as -a and omits any scaling factor, without much to do. For the casual but interested reader, this leads to some confusion when trying to make sense of some following comments about a. This type of switcheroo happens again later in section 3.0, where three definitions in the one section have the exponent as k twice and \alpha once.
I am going to unify all of these places to k. This might also help correct some of the confusion between a and \alpha mentioned elsewhere in this talk page. In the more mathematically rigorous later sections (3.2 Variants and beyond), leaving \alpha as is, as it seems to be used consistently .
--Se7ens (talk) 02:58, 27 March 2017 (UTC)
thread_title:  Confusing exponent notation switches 

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thread_title:  External links modified 

message: The article uses the exponent \alpha for the PDF when the norm is to do so with the survival function to fit extreme value theory and the notation for the stable distribution upon convergence. I suggest changing the notation unless someone has some good reason against it. The reason is that I am teaching a class in the fall and the students may be confused. Limit-theorem (talk) 12:12, 20 July 2018 (UTC)
thread_title:  Notation for the Exponent 

message: I've got a distribution with an exponent of (exactly) 0.5 (its some genomic data). What other examples have this exponent? It would be nice if there was a list of examples, by power value... 67.198.37.16 (talk) 18:02, 24 February 2020 (UTC)
thread_title:  List of different exponent values 

message: The "reference" provided links directly to an open MS Word document file hosted on a Wordpress Blog.  
The Link: http://thomaslillmadsen.dk/wp-content/uploads/2016/11/THE-POWER-DISTRIBUTION-AS-A-MODEL-FOR-CRIMINAL-CAREERS.doc
This blog also has multiple (controversial) articles about criminology in the same open MS Doc format.
A quick search on both regular Google as well as Google Scholar fails to find anything. Potentially original, unpublished (& thus unverified) research? 
I cannot find any research articles by the same name, neither by a Madsen or anyone else with another name. This needs to be flagged & investigated by someone who has experience with this kinda stuff.  — Preceding unsigned comment added by 49.36.117.82 (talk) 10:00, 24 December 2020 (UTC)
thread_title:  Criminology Example 

message: The Empirical Examples section doesn’t explain the relationships between variables, or even what the variables are. E.g. “ these include the sizes of craters on the moon and of solar flares,” The implication could be that power laws describe a relationship between the size of craters on the moon and solar flares. -MultiPoly (talk) 16:39, 17 June 2022 (UTC)
thread_title:  Empirical Examples are unclear 

message: This article seems to be written from the perspective of an expert, and directed toward other experts. Much background information is omitted, and assumptions are made. E.g. what is the variable k? -MultiPoly (talk) 16:39, 17 June 2022 (UTC)
thread_title:  Many assumptions about the reader 

message: the article's main picture references a junk science concept known as the "80-20 principle" (which is literally just a business consulting framewoek for farming vlients for money and firing "low performing" employees), and really should be removed in favor of a valid scientific power law model like idk, globular cluster light curves?
there's numerous other power law models given in this article
make the picture one that isn't some arbitrary business bullcrap picture 2600:6C47:A0F0:8390:F0D3:B1BA:CD37:E632 (talk) 15:28, 16 July 2023 (UTC)
thread_title:  the articles main picture needs to be changed 

message: "Pareto's law" is a junk science concept that has no valid place in this article 2600:6C47:A0F0:8390:F0D3:B1BA:CD37:E632 (talk) 15:29, 16 July 2023 (UTC)
replies: text: This us about the Pareto distribution, not the popular Pareto law although the two may be linked (the latter is inspired from the former). Limit-theorem (talk) 18:29, 16 July 2023 (UTC)
thread_title:  remove references to "Pareto's law"