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Topic: Regression toward the mean

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	Regression toward the mean - Wikipedia, the free encyclopedia
		In statistics, regression toward the mean is a principle stating that of related measurements, and selecting those where the first measurement is either higher or lower than the average, the expected value of the second is closer to the mean than the observed value of the first.
		The phenomenon of regression toward the mean is related to Stein's example.
		A non-mathematical explanation of regression toward the mean.
	en.wikipedia.org /wiki/Regression_toward_the_mean (1819 words)

	Regression - Wikipedia, the free encyclopedia
		Generally, regression is a move backwards; It is the opposite of progression.
		A method where the mean of one or more random variables is predicted conditioned on other (measured) random variables.
		In psychology, regression is believed to be a defense mechanism of the ego, where a person reacts to failure with an immature response.
	en.wikipedia.org /wiki/Regression (282 words)

	Do Statistics Test Scores Regress Toward the Mean?
		For a test of the null hypothesis that the slope is equal to 1, which would deny regression toward the mean, the t value is 14.8 and the P value is again minuscule.
		However, the purely statistical theory of regression toward the mean works in either direction, since those who obtained the highest (or lowest) scores on a test are predicted to be more nearly average on another test, regardless of whether it precedes or follows the current test.
		Regression toward the mean is confirmed: students who scored 10 points above (or below) the mean on the final examination tended to score 5.7 points above (or below) the mean on the midterm.
	www.economics.pomona.edu /GarySmith/StatsRegress/StatsRegress.html (2481 words)

	Links on Regression to the Mean
		Regression toward the mean (R2M) is a fascinating concept that is both useful and easy to apply.
		Regression to the mean is a technical term in probability and statistics.
		Don considered regression to the mean to be one of his most important contributions in the field of methodology.
	tasponline.org /r2m.htm (899 words)

	Regression to the Mean
		A regression threat, also known as a "regression artifact" or "regression to the mean" is a statistical phenomenon that occurs whenever you have a nonrandom sample from a population and two measures that are imperfectly correlated.
		The bottom of the figure shows where the sample's posttest mean would have been without regression and where it actually is. In actuality, the sample's posttest mean wound up closer to the posttest population mean than their pretest mean was to the pretest population mean.
		Regression to the mean is one of the trickiest threats to validity.
	www.socialresearchmethods.net /kb/regrmean.htm (1939 words)

	Regression Toward the Mean (3 of 6)
		This is the phenomenon called "regression toward the mean." Regression toward the mean occurs any time people are chosen based on observed scores that are determined in part or entirely by chance.
		This means that the predicted standardized score will be closer to the mean of zero whenever the correlation is not perfect (not -1 or 1).
		For example, if the SAT had a mean of 500 and a standard deviation of 100, then a score of 750 would have a standard score equivalent of 2.5 since 750 is two and a half standard deviations above the mean.
	davidmlane.com /hyperstat/B154335.html (422 words)

	Gene Expression: Regression to the Mean and Galton’s Fallacy (not!)
		Regression to the Mean and Galton’s Fallacy (not!)
		regressed toward the mean; similarly, the fathers of tall sons tended to be shorter than their sons, i.e.
		If the mean of these standardised y values is closer to the standardised mean of all the y’s than the mean of the associated standardised x values is to the standardised mean of all the x’s, then we may say that the y’s regress towards the mean.
	www.gnxp.com /MT2/archives/002573.html (2835 words)

	A look at the inheritance of height using regression toward the mean Human Biology - Find Articles
		By acknowledging that the father may be incorrectly identified, this new analysis provides a more relevant explanation of the data: it fits parallel regression lines for sons and daughters, and is consonant with the theory that each parent contributes equally to the genetic makeup of their offspring, at least as far as height is concerned.
		This phenomenon, where the offspring might be viewed as tending toward the population average, is presently referred to as regression toward the mean, although it started off as regression to mediocrity (Kendall and Stuart 1979).
		To overcome the problem Galton had simply multiplied the heights of the mothers by 1.08 (based on the ratio of the mean male height and mean female height), and then averaged the parents' heights to obtain the midparent height.
	www.findarticles.com /p/articles/mi_qa3659/is_200006/ai_n8883243 (955 words)

	Do Baseball Players Regress Toward the Mean
		These disappointments might be explained by regression toward the mean, which occurs when real phenomena are measured imperfectly, causing extreme measurements to exaggerate differences among the underlying phenomena.
		Galton (1886) observed regression toward the mean in his seminal study of the relationship between the heights of parents and their adult children.
		The mean batting average was approximately 30 points lower in the adjacent seasons than in the top-10 season; the mean earned run average was roughly 1 run higher.
	www.economics.pomona.edu /GarySmith/BBregress/baseball.html (2572 words)

	Regression to Mean vs Progression to Individual Differences
		Although formulas that use regression toward the mean are currently touted as a statistically informed and improved method for identifying learning disabilities, they in fact appear to be particularly ill suited to the job of identification.
		At the heart of the issue is whether a model that assumes drift toward the mean (average) is suitable in the context of those atypicalities of learning disability that are, by nature, in defiance of the mean.
		Formulas that regress predicted achievement scores toward the mean based on full scale IQ are at the very least inappropriate to the identification of learning disabilities and more probably obfuscating and detrimental.
	educational-advisor.com /regression.html (4525 words)

	Dr. Jim Taylor
		In order to ensure that the decline is not due to a regression toward the mean, it is proposed that evidence of a "rebound effect" must also be present for a decrement in performance to be considered a sophomore slump.
		The latter notion of the rebound effect is critical in that it distinguishes a sophomore slump from a regression toward the mean of ability.
		It should also be pointed out that the findings in support of the regression toward the mean explanation may be interpreted in a manner that is also consistent with the notion of the sophomore slump as presently conceptualized.
	www.drjimtaylor.com /homtemplate/sophomoreslump.html (2489 words)

	Decision Science News: Wily regression to the mean
		This conclusion is unwarranted because of the presence of regression toward the mean.
		Regression to the mean is like the cicada, just as you forget about it, you hear its buzz.
		"Galton's completion of his discovery of this phenomenon [regression to the mean] in the 1880s should rank should rank with the greatest individual events in the history of science—at a level with William Harvey's discovery of the circulation of blood and with Isaac Newton's of the separation of light."
	www.dangoldstein.com /dsn/archives/2006/03/wily_regression.html (523 words)

	POWERMUTT: Regression Analysis
		It is called regression analysis because Francis Galton (1822-1911), a pioneer in the application of OLS to the behavioral sciences, used it to study “regression toward the mean.”[2] Regression analysis is a simple but extremely powerful technique with a wide variety of applications.
		In an unstandardized regression equation in which the dependent variable is a “feeling thermometer” for Hillary Clinton, a “b” coefficient of 8.106 associated with gender would mean that, all else being equal, women rate her a little more than 8 points higher than do men.
		What does it mean, for example, to say that an increase of one standard deviation in household composition is associated with an increase of.255 standard deviations in party id? Because unstandardized and standardized equations each have their strengths and limitations, it is helpful to have both.
	www.csupomona.edu /~jlkorey/POWERMUTT/Topics/regression.html (3362 words)

	REGRESSION TOWARD THE MEAN
		Regression to the mean is a statistical phenomenon that is a fact of life in statistics.
		The net effect of regression toward the mean is that the lower scores (or measurements) on the pretest tend to be higher on the posttest, and the higher scores (or measures) on the pretest tend to be lower on the posttest.
		Regression toward the mean is expected in these cases where there is non-random sampling or assignment in experiments.
	www.socialresearchmethods.net /tutorial/Cheng/lcheng.htm (1081 words)

	bmj.com Rapid Responses for Bland and Altman, 308 (6942) 1499
		After reading "regression towards the mean" (BMJ:1994:308:1499) I felt compelled to share some helpful information related to regression that is not present in most published literature on the topic.
		The regression toward the mean simply minimizes the vertical distances of the points from the fitted Y vs X line and the equations are well known.
		Always using regression toward the mean to minimize vertical distances, especially for elliptical looking data with variability on X and Y is mediocrity.
	bmj.bmjjournals.com /cgi/eletters/308/6942/1499 (852 words)

	Adjusting for regression toward the mean when variables are normally distributed.
		Adjusting for regression toward the mean when variables are normally distributed.
		As a consequence, if not properly accounted for, the effect of regression toward the mean can confound the evaluation of treatment effects if the study has no randomized control group.
		In this paper we review the methods that have been proposed for adjusting for the effect of regression toward the mean when the variable of interest is assumed to be normally distributed.
	www.aegis.com /aidsline/1997/dec/M97C0950.html (347 words)

	Lecture 6
		The sign of the correlation coefficient determines whether a relationship is described by a regression line of positive or negative slope.
		Regression is no better suited to determining causation than correlation if the research methods of data collection do not warrant it.
		Regression is frequently used for the purpose of prediction.
	www.american.edu /academic.depts/cas/health/dhf/HFIT565/notes6.html (2232 words)

	Amazon.ca: A Primer on Regression Artifacts: Books: Donald T. Campbell,David A. Kenny (Site not responding. Last check: 2007-08-20)
		In either case, you will find that the authors meet you more than halfway; they guide your inquiry with ample encouragement, engaging illustrations, and good humor....It is hard to imagine a duo that is more capable of making comprehensible a challenging methodological topic." --This text refers to the Hardcover edition.
		Regression toward the mean is a complex statistical principle that plays a crucial role in any research involving the measurement of change.
		The book presents new methods of graphing regression toward the mean, facilitating comprehension with a wealth of figures and diagrams.
	www.amazon.ca /A-Primer-on-Regression-Artifacts/dp/1572308591 (451 words)

	[No title]
		Applying regression analysis: Results of a small sample study In 1998, Frankenberger, Volpiansky, Burgess, Moline, Vershay, Doherty, Stauss, and Wingen (unpublished paper) completed a study comparing the four most commonly used methods for determining significant discrepancy between intellectual ability and academic achievement (SLRM, Reynolds, Bond and Tinker, and SS cut-off).
		While the Reynolds Formula and the SLRM identified students with mean IQs that approached the population mean (102.8 and 102.9 respectively), the Bond and Tinker Formula identified students with lower mean IQs (94.9), and the SS Cut-off Method identified students with considerably higher mean IQs (110.5).
		Based on the mean populations identified by each method investigated in this study, the authors conclude that the two regression formulas are more technically sound with respect to identifying ability/achievement discrepancies in students than the Bond and Tinker Formula or the SS Cut-off Method.
	www.dpi.state.wi.us /sped/doc/elgldpaper.doc (1913 words)

	Card Player Magazine - The Peter Principle and Regression Toward the Mean by Daniel Kimberg
		Regression toward the mean is a statistical principle that explains why the results of extreme performers tend to overestimate their true abilities.
		This doesn't mean that everyone who wins at poker is really a loser, and there are likely some players who, even with their impressive results, are actually better players than their results would seem to indicate.
		Regression toward the mean is a statistical/logical necessity, while the Peter Principle is just a reflection of something organizations do poorly, but conceivably don't have to.
	www.cardplayer.com /magazine/article/15171 (1354 words)

	SparkNotes: Psychological Treatment: Effectiveness of Treatment
		Regression toward the mean: People often go into treatment because they are in extreme distress.
		The tendency for extreme states to move toward the average when assessed a second time is called regression toward the mean.
		Regression toward the mean affects providers’ perceptions of success.
	www.sparknotes.com /psychology/psych101/treatment/section6.rhtml (627 words)

	Critical Thinking (phil158d): Regression & Grades
		On a deep level, these two conditions may be ways of saying the same thing: if there is no "typical" result, then there will be no extremes and no mean to regress toward.
		The reason this phenomenon is called "regression toward the mean" (and not regression-all-the-way-back-to-the-mean) is the assumption that the exceptional result is a partially accurate measure of the underlying quality (or qualities) that lead to that result.
		So, for instance, the fact that a player wins the rookie-of-the-year award indicates that he's a better-than-average first-year player; but it doesn't show that over the next few years he will continue to be the best of that crop of players.
	www.queensu.ca /philosophy/courses/phil158d/numbers/r2m.htm (582 words)

	regressive fallacy
		The regressive fallacy is the failure to take into account natural and inevitable fluctuations of things when ascribing causes to them (Gilovich 1993: 26).
		This tendency to move toward the average away from extremes was called "regression" by Sir Francis Galton in a study of the average heights of sons of very tall and very short parents.
		(The study was published in 1885 and was called "Regression Toward Mediocrity in Hereditary Stature.") He found that sons of very tall or very short parents tend to be tall or short, respectively, but not as tall or as short as their parents.
	skepdic.com /regressive.html (774 words)

	The Emerging Democratic Majority WebLog - DonkeyRising
		Some of this might be explained by the well known phenomenon of regression toward the mean.
		Every poll that was above the overall mean in early October was below the overall mean in late October and every poll that was below the overall mean in in early October was above the overall mean in late October.
		What this bizarre pattern suggests is that the movements of the major media polls in October, like the movements of the tracking polls, reflect sampling error and peculiarties of the polls rather than real change in the underlying preferences of the electorate.
	emergingdemocraticmajorityweblog.com /donkeyrising/archives/000851.php (603 words)

	Statistic Notes: Regression towards the mean -- Bland and Altman 308 (6942): 1499 -- BMJ
		Statistic Notes: Regression towards the mean -- Bland and Altman 308 (6942): 1499 -- BMJ
		parents was to the mean height of all parents.
		Galton F. Regression towards mediocrity in hereditary stature.
	bmj.bmjjournals.com /cgi/content/full/308/6942/1499 (1250 words)

	COGNITIVE PERFORMANCE AFTER CARDIAC OPERATION: IMPLICATIONS OF REGRESSION TOWARD THE MEAN -- Browne et al. 117 (3): 481 ...
		of regression toward the mean on different definitions of cognitive
		the mean on 3 commonly used single-case definitions of cognitive
		mean was demonstrated on both tests by classifying the preoperative
	jtcs.ctsnetjournals.org /cgi/content/abstract/117/3/481 (826 words)

	A Primer on Regression Artifacts
		Campbell and Kenny have produced a book on this topic that is destined to be a classic.
		Ideally suited for graduate students in the social sciences and for nonexperimental researchers, the book is comprehensive and accessible....Producers as well as critical consumers of empirical information will want this text on their shelves."
		He has been a visiting professor at Oxford University and Arizona State University, and was a Fellow at the Center for Advanced Study in the Behavioral Sciences.
	guilford.com /cgi-bin/cartscript.cgi?page=pr/campbell3.htm&... (460 words)

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