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Topic: Null hypothesis

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	Null hypothesis - Wikipedia, the free encyclopedia
		When used, the null hypothesis is presumed true until statistical evidence in the form of a hypothesis test indicates otherwise.
		The use of the null hypothesis is controversial.
		For example, if the null hypothesis is that sample A is drawn from a population with the same mean as sample B, the alternative hypothesis is that they come from populations with different means, which can be tested with a two-tailed test of significance.
	en.wikipedia.org /wiki/Null_hypothesis (1090 words)

	PlanetMath: hypothesis testing
		Hypothesis testing is a statistical inferencial procedure in which a statement based on some experimental or observational study is formulated, tested, then put through a decision process.
		When a statement (whether it is null hypothesis or the alternative hypothesis) is accepted, it merely says that, statistically, there is not enough evidence to reject the statement.
		This is version 2 of hypothesis testing, born on 2004-10-07, modified 2005-02-28.
	planetmath.org /encyclopedia/NullHypothesis.html (359 words)

	Hypothesis Testing
		Hypothesis testing and estimation are used to reach conclusions about a population by examining a sample of that population.
		Hypothesis testing is widely used in medicine, dentistry, health care, biology and other fields as a means to draw conclusions about the nature of populations.
		The decision rule says to reject the null hypothesis if the value of the test statistic is in the rejection region and not to reject the null hypothesis if it falls in the nonrejection region.
	www.kean.edu /~fosborne/bstat/07hyp.html (1103 words)

	Null Hypothesis (1 of 4) (Site not responding. Last check: 2007-11-06)
		The null hypothesis is an hypothesis about a population parameter.
		The purpose of hypothesis testing is to test the viability of the null hypothesis in the light of experimental data.
		The null hypothesis is often the reverse of what the experimenter actually believes; it is put forward to allow the data to contradict it.
	davidmlane.com /hyperstat/A29337.html (162 words)

	Statistics Glossary - hypothesis testing
		A hypothesis might also be a statement about the distributional form of a characteristic of interest, for example that the height of ten year old boys is normally distributed within the Scottish population.
		If we do not reject the null hypothesis, it may still be false (a type II error) as the sample may not be big enough to identify the falseness of the null hypothesis (especially if the truth is very close to hypothesis).
		The critical value(s) for a hypothesis test is a threshold to which the value of the test statistic in a sample is compared to determine whether or not the null hypothesis is rejected.
	www.stats.gla.ac.uk /steps/glossary/hypothesis_testing.html (2225 words)

	Null Hypothesis - SkepticWiki (Site not responding. Last check: 2007-11-06)
		In statistics, the null hypothesis (contrast with the experimental hypothesis or alternate hypothesis) is a statement describing the baseline effect if no treatement or experimentation has any effect at all.
		The task of hypothesis testing is to determine which of the two competing hypotheses is better supported by the evidence.
		Statisticians usually evaluate hypotheses in terms of a p-value, the likelihood that the null hypothesis would have produced at least as extreme a distribution as the one observed.
	www.skepticwiki.org /wiki/index.php?title=Null_Hypothesis&printable=yes (663 words)

	The Null Hypothesis
		The null hypothesis, no matter what test statistic is used, is that there is no differential effect of the treatments for any of the subjects.
		The null hypothesis was no difference in the treatment effect for any subject, and that is the same null hypothesis tested if we expect a difference in variability of treatment effects and use a test statistic sensitive to that property.
		And if we run a randomization test and reject the null hypothesis, that might mean that the reason why we have rejected the hypothesis is because one treatment led to a larger mean, or greater variability, or a more skewed distribution than did the other.
	www.uvm.edu /~dhowell/StatPages/Resampling/null_hypotheses.html (1133 words)

	Significance Tests / Hypothesis Testing
		The null hypothesis is usually stated as the absence of a difference or an effect.
		The probability of the rejecting the null hypothesis increases with the difference between population means.
		For example, for a fixed sample size, the probability of failing to reject a null hypothesis of equal population means decreases as the difference between population means increases.
	www.tufts.edu /~gdallal/sigtest.htm (1741 words)

	null hypothesis, nonconformance
		NULL HYPOTHESIS A tentative explanation which indicates that a chance distribution is operating; a contrast to the alternate hypothesis.
		Despite the "null" in "null hypothesis," there are occasions when the parameter is not hypothesized to be 0.
		For example the null hypothesis may be that the parameter is equal to a specific value.
	www.adamssixsigma.com /Glossary_of_terms/six_sigma_glossary_N.htm (630 words)

	Hypothesis Testing (Site not responding. Last check: 2007-11-06)
		Hypothesis testing is one of the most important tools of application of statistics to real life problems.
		Always the null hypothesis is tested, i.e., we want to either accept or reject the null hypothesis because we have information only for the null hypothesis.
		A related concept is power, which is the probability of rejecting the null hypothesis when it is actually false.
	ewr.cee.vt.edu /environmental/teach/smprimer/hypotest/ht.html (2437 words)

	HYPOTHESIS TESTING (Site not responding. Last check: 2007-11-06)
		A statistical hypothesis is a claim or a statement about the value of a single parameter or about the values of several parameters.
		A statistical test of hypothesis is a method for deciding which of the two hypotheses is correct and is based on the method of proof by contradiction.
		In hypothesis testing, this error is the same as rejecting the null hypothesis when it is true.
	www.fiu.edu /~gulati/hypothesis.htm (730 words)

	Null Hypothesis (from Internet Glossary of Statistical Terms)
		The null hypothesis is a term that statisticians often use to indicate the statistical hypothesis tested.
		In this example, the hypothesis tested is that the two samples are from populations with the same mean.
		Another way to say this is to assert that the investigator tests the null hypothesis that the difference between the means of the populations from which the samples were drawn, is zero.
	www.animatedsoftware.com /statglos/sgnullhy.htm (246 words)

	The null oncogene hypothesis and protection from cancer -- Davenport et al. 39 (1): 12 -- Journal of Medical Genetics
		By contrast, the constitutive inactivation of a proto-oncogene produces the "null oncogene effect" and reduces the risk of both sporadic and familial cancer by half (C).
		The null oncogene hypothesis predicts that the presence of a
		However, the null oncogene hypothesis predicts that mutations which result in a complete loss of function of RET should lead to Hirschsprung disease and a reduced rate of thyroid carcinoma (C).
	jmg.bmjjournals.com /cgi/content/full/39/1/12 (1906 words)

	Statistical Hypothesis Testing
		Null means "nothing," and the null hypothesis is that nothing is present.
		If the null hypothesis is true, there is a 5 percent chance of rejecting it because of random variation (luck).
		It is the integral of the distribution from 0 to 12.59, and 95 percent of the area under the curve is to the left of 12.59.
	www.ganesha.org /spc/hyptest.html (1256 words)

	Hypotheses (Site not responding. Last check: 2007-11-06)
		There is no formal hypothesis, and perhaps the purpose of the study is to explore some area more thoroughly in order to develop some specific hypothesis or prediction that can be tested in future research.
		The way we would formally set up the hypothesis test is to formulate two hypothesis statements, one that describes your prediction and one that describes all the other possible outcomes with respect to the hypothesized relationship.
		Usually, we call the hypothesis that you support (your prediction) the alternative hypothesis, and we call the hypothesis that describes the remaining possible outcomes the null hypothesis.
	www.socialresearchmethods.net /kb/hypothes.htm (788 words)

	Hypothesis Testing -- from Wolfram MathWorld
		Hypothesis testing is the use of statistics to determine the probability that a given hypothesis is true.
		Identify a test statistic that can be used to assess the truth of the null hypothesis.
		Compute the P-value, which is the probability that a test statistic at least as significant as the one observed would be obtained assuming that the null hypothesis were true.
	mathworld.wolfram.com /HypothesisTesting.html (244 words)

	Explaining Significance and Hypothesis Testing [TimeWeb ]
		The Null Hypothesis is, in the case of Group A claims, the assertion that there is no difference between the sample we have collected and the general population established by the claim.
		For Group B claims, the Null Hypothesis is that there is no difference between the two populations in the study.
		The Alternative Hypothesis for Group A claims, is that the sample you have belongs to a population different from that described in the original claim.
	www.bized.co.uk /timeweb/crunching/crunch_experiment_expl.htm (992 words)

	Alternatives to Null Hypothesis Significance Testing
		The emphasis on hypothesis testing produces a concomitant de-emphasis of an alternative technique for coping with statistical error that is simple, direct, and intuitive and that has wide acceptance in the natural sciences: the use of confidence intervals.
		The null hypothesis, which merely represents the distribution (i.e., model) that the data are distributed according to chance would indeed be rejected if a more plausible model were found to better account for the data.
		They argue that as an alternative to null testing, a comparison of alternative hypotheses does not simply reject a “meaningless” null hypothesis, but rather compares how the data fit any one of the posited alternatives by means of the maximum likelihood ratio.
	theoryandscience.icaap.org /content/vol4.1/02_denis.html (11065 words)

	Statistics Solutions: Hypothesis Testing
		Typically, researchers state a hypothesis as a “null hypothesis (abbreviated as H o).” That is, there is no difference in the dependent variable by the independent variable.
		The results of hypothesis testing are to correctly reject the null, correctly retain the null hypothesis, or result in a Type I or Type II error.
		The researcher states the null hypothesis and the alternative hypotheses to be examined.
	www.statisticssolutions.com /Hypothesis_Testing.htm (443 words)

	Null Hypothesis and "p value" (Site not responding. Last check: 2007-11-06)
		One of the first steps in the decision-making procedure is to state the null hypothesis.
		The null hypothesis is assumed to be true unless the data cause the researcher to reject it.
		The term "p value" means that under the null hypothesis of no difference between groups the observed difference between groups (or a larger difference) will occur with the probability "p" with random sampling.
	nsm1.nsm.iup.edu /rwinstea/null-p.shtm (540 words)

	Statistics Glossary - Hypothesis Testing
		For example, in a clinical trial of a new drug, the null hypothesis might be that the new drug is no better, on average, than the current drug; that is H
		That is, nothing specific can be said about the average number of matches in a box; only that, if we could reject the null hypothesis in our test, we would know that the average number of matches in a box is likely to be less than or greater than 50.
		Presumably, we would want to test the null against the first alternative hypothesis since it would be useful to know if there is likely to be less than 50 matches, on average, in a box (no one would complain if they get the correct number of matches in a box or more).
	www.cas.lancs.ac.uk /glossary_v1.1/hyptest.html (2167 words)

	Classics in the History of Psychology -- Rozeboom (1960)
		All that is required is that the degree of belief arrived at be in general inappropriate to the likelihood conferred on the hypothesis by the data.
		This likelihood of the hypothesis relative to whatever data are available at the moment will be an important determinant for decisions which must currently be made, but is not itself such a decision and is entirely subject to revision in the light of additional information.
		Acceptance or rejection of a hypothesis is a cognitive process, a degree of believing or disbelieving which, if rational, is not a matter of choice but determined solely by how likely it is, given the evidence, that the hypothesis is true.
	psychclassics.yorku.ca /Rozeboom (5161 words)

	INTERPRETING FAILURE TO REJECT A NULL HYPOTHESIS (Site not responding. Last check: 2007-11-06)
		My argument is with the interpretation, in hypothesis testing, that failure to reject the null hypothesis is proof of the null hypothesis.
		Failing to reject a null hypothesis is distinctly different from proving a null hypothesis; the difference in these interpretations is not merely a semantic point.
		Unfortunately, the notion of accepting the null hypothesis is suggested by at least one important textbook (Sokal and Rohlf 1981, e.g., pages 172, 190, and 224), and the idea seems to be widely held.
	www.harding.edu /USER/plummer/WWW/biostats/acceptreject.htm (854 words)

	Hypothesis testing and power
		In our example, which states a null hypothesis in terms of the population mean, a relevant test statistic is the t.
		The figure illustrates that we retain (fail to reject) the null hypothesis if xbar is equal to or between the critical values we have calculated.
		Failing to reject the null hypothesis is an incorrect decision.
	moon.ouhsc.edu /dthompso/CDM/power/hypoth.htm (3108 words)

	Hypothesis Testing
		The standard OLS estimation output from SHAZAM reports a t-ratio for testing the null hypothesis that the true regression coefficient is zero.
		However, the null hypothesis will be rejected only if the value of the test statistic is excessively large (giving support to the alternative hypothesis).
		For a one-sided test of the null hypothesis that the income elasticity is less than or equal to 1 against the alternative that the income elasticity is greater than 1 the p-value is
	shazam.econ.ubc.ca /intro/olstest.htm (938 words)

	Null result - Wikipedia, the free encyclopedia
		Generally, a null result is a result which is null (nothing): that is, the proposed result is absent.
		This is considered evidence for the null hypothesis.
		In logic, a null result is an invalid value of a proposition.
	en.wikipedia.org /wiki/Null_result (327 words)

	The Null Hypothesis
		It would be easy to disprove this hypothesis by producing just one bit of period writing that does connect the two, but as scholars have proven no such document has survived.
		However the Null Hypothesis suggests this assumption was only warranted in ignorance and points out that no one in this small group left a word about it that has survived to this day.
		The Null Hypothesis maintains that as long as we _separate_ these three circles there is no Shakespeare/Shakspere problem until 1623, when two of them are forcibly conjoined in the First Folio.
	www2.localaccess.com /marlowe/null.htm (5662 words)

	Research Methods - Developing the Hypothesis in AllPsych Online
		The null hypothesis is always written with the assumption that the groups do not differ.
		The null hypothesis is what we test through the use of statistics and is abbreviated H
		If we, however, show that the null is not true then we must reject it and therefore conclude that the alternative hypothesis must be true.
	allpsych.com /researchmethods/developingthehypothesis.html (381 words)

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