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Topic: Significance level

	[No title]
		Significance is the percent chance that a relationship found in the data is just due to an unlucky sample, such that if we took another sample we might find nothing.
		Thus significance has a different meaning when, for example, the confidence interval is the entire range of the data, as compared to the situation where the confidence interval is only ten percent of the range.
		Obviously, the.80 level of power is arbitrary and the researcher must set the level appropriate for his or her research needs.
	www.statisticssolutions.com /Significance.htm (1207 words)

	Statistical significance - Wikipedia, the free encyclopedia
		More precisely, in traditional frequentist statistical hypothesis testing, the significance level of a test is the maximum probability of accidentally rejecting a true null hypothesis (a decision known as a Type I error).
		The significance of a result is also called its p-value; the smaller the p-value, the more significant the result is said to be.
		For example, one may choose a significance level of, say, 5%, and calculate a critical value of a statistic (such as the mean) so that the probability of it exceeding that value, given the truth of the null hypothesis, would be 5%.
	en.wikipedia.org /wiki/Statistical_significance (386 words)

	Probability of a statistic and its significance level (Site not responding. Last check: 2007-11-07)
		Probability of a statistic and its significance level
		The significance of a statistic is its probability of occurrence assuming the null hypothesis is true
		In the previous example, the probability of obtaining a mean of 1.5 (or higher) from a population assumed to have a mean of zero is.025
	www.les.appstate.edu /courses/research/Session9/tsld011.htm (57 words)

	Statistical Significance
		In contrast the high significance level for type of vehicle (.001 or 99.9%) indicates there is almost certainly a true difference in purchases of Brand X by owners of different vehicles in the population from which the sample was drawn.
		The 95% level comes from academic publications, where a theory usually has to have at least a 95% chance of being true to be considered worth telling people about.
		For example, if the significance level is.05 then you could consider the likelihood that there is a difference in the population to be 95% (1-.05).
	www.surveysystem.com /signif.htm (1299 words)

	Significance Level: Encyclopedia of Psychology
		The ultimate goal is to determine whether the difference would occur if the measurements were administered a second time, or whether the difference is accidental and not likely to recur.
		The degree of reliability relates to the concept of significance level.
		The significance level refers to how likely it is that an error (that is, a wrong decision about whether the groups differ from one another) would be made.
	www.enotes.com /gale-psychology-encyclopedia/significance-level (168 words)

	II. Sampling Error and Statistical Significance (Site not responding. Last check: 2007-11-07)
		As indicated in the footnotes, significant differences are noted by "a" (significant at the.05 level of significance) and "b" (significant at the.01 level of significance).
		Also, keep in mind that while a level of significance equal to.05 is used to determine statistical significance in these tables, large differences associated with slightly higher p-values (specifically those between.05 and.10) may be worth noting along with the p-values.
		Furthermore, statistically significant differences are not always meaningful, because the magnitude of difference may be small or because the significance may have occurred simply by chance.
	www.oas.samhsa.gov /nhsda/ar18t056.htm (531 words)

	[No title]
		The significance level and the power of a test are the probability of the same event, the event that the null hypothesis is rejected.
		The difference between significance level and power is the assumption about the world we use to compute the probability: to compute the significance level, we assume that the null hypothesis is true; to compute the power, we assume that the alternative hypothesis is true.
		The significance level of an hypothesis test is the chance that the test rejects the null hypothesis, on the assumption that the null hypothesis is true.
	www.stat.berkeley.edu /users/stark/SticiGui/Text/ch19.htm (7510 words)

	1
		The observed significance level of a statistical test was 0.00423.
		Accept at the 0.01 level of significance and reject at the 0.05 level.
		Accept at the 0.05 level of significance and reject at the 0.10 level.
	www.ams.sunysb.edu /~finchs/f98final.html (2280 words)

	TTest (Math 1.0 API) (Site not responding. Last check: 2007-11-07)
		Returns the observed significance level, or p-value, associated with a two-sample, two-tailed t-test comparing the means of the input arrays, under the assumption that the two samples are drawn from subpopulations with equal variances.
		The number returned is the smallest significance level at which one can reject the null hypothesis that the mean of the paired differences is 0 in favor of the two-sided alternative that the mean paired difference is not equal to 0.
		The number returned is the smallest significance level at which one can reject the null hypothesis that the two means are equal in favor of the two-sided alternative that they are different.
	jakarta.apache.org /commons/math/api/org/apache/commons/math/stat/inference/TTest.html (2731 words)

	Hypothesis Tests (Statistics Toolbox)
		The significance level is related to the degree of certainty you require in order to reject the null hypothesis in favor of the alternative.
		For this significance level, the probability of incorrectly rejecting the null hypothesis when it is actually true is 5%.
		That is equivalent to being unable to reject the null hypothesis at a significance level of 0.05.
	www.technion.ac.il /guides/matlab/toolbox/stats/hypothe2.html (286 words)

	Untitled (Site not responding. Last check: 2007-11-07)
		To give the user some insight, the critical values bounding the desired significance level are printed with the associated significance and power values whenever either value is changed from that requested.
		The inability to exactly match requested significance levels is the reason that two-sided tests are not considered in the one-sample Poisson case.
		Because significance levels are not generally attained, this condition cannot be exactly achieved in the one-sample binomial case.
	calculators.stat.ucla.edu /powercalc/poisson/1/help.php (717 words)

	Significance Level
		In hypothesis testing, the significance level is the criterion used for rejecting the null hypothesis.
		The significance level is used in hypothesis testing as follows: First, the difference between the results of the experiment and the null hypothesis is determined.
		If the probability is less than or equal to the significance level, then the null hypothesis is rejected and the outcome is said to be statistically significant.
	davidmlane.com /hyperstat/A72117.html (171 words)

	Statistical significance (Site not responding. Last check: 2007-11-07)
		Significance tests are performed to see if the null hypothesis can be rejected.
		The experimenter chooses a significance level before conducting the statistical analysis.
		The significance level chosen determines the probability of a Type I error.
	www.ruf.rice.edu /~lane/hyperstat/A71266.html (77 words)

	Statistics Glossary - hypothesis testing
		The significance level of a statistical hypothesis test is a fixed probability of wrongly rejecting the null hypothesis H
		That is, we want to make the significance level as small as possible in order to protect the null hypothesis and to prevent, as far as possible, the investigator from inadvertently making false claims.
		Usually, the significance level is chosen to be 0.05 (or equivalently, 5%).
	www.stats.gla.ac.uk /steps/glossary/hypothesis_testing.html (2225 words)

	P values
		For example, if a P value is 0.027, the results are significant for all fixed levels greater than 0.027 (such as 0.05) and not significant for all fixed levels less than 0.027 (such as 0.01).
		However, significance tests provide a useful summary of the data and these concerns are easily remedied by supplementing significance tests with the appropriate confidence intervals for the effects of interest.
		Significance tests can tell us whether a difference between sample means is statistically significant, that is, whether the observed difference is larger than would be due to random variation if the underlying population difference were 0.
	www.tufts.edu /~gdallal/pval.htm (2559 words)

	ttest :: Functions (Statistics Toolbox)
		indicates a rejection of the null hypothesis at the 5% significance level.
		indicates a failure to reject the null hypothesis at the 5% significance level.
		Notice that at the lowered significance level the 99% confidence interval on the mean widens to contain 0.
	www.mathworks.com /access/helpdesk/help/toolbox/stats/ttest.html (515 words)

	[No title]
		The notion of soma- significance implies that soma (or the physical) and its significance (which is mental) are not separate in the sense that soma and psyche are generally considered to be; rather they are two aspects of one overall indivisible reality.
		From each level of somatic unfoldment of meaning, there is then a further movement leading to activity on to a yet more manifestly somatic level, until the action finally emerges as a physical movement of the body that affects the environment.
		This action may initially be based partly on a kind of significance that objects have which is grounded in the accumulated instinctive response to the experience of the species, and partly on a kind of significance that is grounded in the past experience of the child itself.
	goertzel.org /dynapsyc/1995/bohm.html (12189 words)

	Statistical significance (Site not responding. Last check: 2007-11-07)
		The level of statistical significance is determined by the probability that this has not, in fact, happened.
		In experiments where we are obliged to resort to statistics it is therefore proper procedure to define a level of significance at which a correlation will be deemed to have been proven, though the choice is often actually made after the event.
		A typical level at which the threshold of P is set would be 0.01, which means there is a one percent chance that the result was accidental.
	www.numberwatch.co.uk /significance.htm (471 words)

	BioMed Central \| Full text \| Allele frequency misspecification: effect on power and Type I error of model-dependent ...
		For a significance level of 0.0001, the power increased from 39% to 56% when the "true" marker allele frequencies of 0.001, 0.24975, 0.24975, 0.24975, and 0.24975 were misspecified as 0.1, 0.225, 0.225, 0.225, and 0.225, respectively.
		Results are presented in Figure 2 for the 0.0001 significance level, using the marker at a recombination fraction of 0.01.
		As shown in Figure 4 for the 0.01 significance level, an increase in Type I error was usually observed when the frequency of the most common allele(s) was decreased (misspecified downward from the true value) and that of the less common allele(s) increased in analysis using a sample-specific estimated trait model.
	www.biomedcentral.com /1471-2156/7/21 (3964 words)

	SEQ, SEQSCALE, and SEQSHIFT Calls
		The probability at the level k=3 at the point x=6 is prob[4,3]=0.96651, while the density at the same point is density[4,3]=0.0000524.
		Note that the continuation at level 2 can be effectively considered infinite, and it does not numerically affect the results of the computation at level 3.
		Hence, the densities and the probabilities reported for the first level at this point are not for the given value -20; instead, they are for the internal value of -8.
	www.asu.edu /it/fyi/dst/helpdocs/statistics/sas/sasdoc/sashtml/iml/chap17/sect212.htm (1988 words)

	Re: Week 14/Significance Level (Site not responding. Last check: 2007-11-07)
		Alpha.05 and alpha.01 are the most common level.
		(.05 = 5% and.01 1%)The smaller the probability level, the larger the mean difference must be in order to be a significant difference.
		The probability level should be decided on prior to conducting the study.
	coe.sdsu.edu /ed690/Discussion/_disc1/0000009d.htm (88 words)

	Marginal Significance
		Psychology, wanting to be as rigorous, adopted that same level and many rigorous purist insist that research is a theory building, hypothesis testing enterprise and any yielding on the.05 level weakens the integrity of research.
		Statistical significance is virtually independent of effect size, which is what educators and doctors and others, as a practical matter, are most concerned with....being more focused on whether the treatment is worth considering in practice.
		Although the conventional level is.05, sometimes there are good reasons that a researcher will set the significance level at a different level.
	ed-web2.educ.msu.edu /DSLTC/marginalsig.htm (642 words)

	Level of significance - Affected Environment and Environmental Consequences (Site not responding. Last check: 2007-11-07)
		Level of Significance of Disparity: =.10; =.05; **=.01.
		At the 10% level of significance, is there sufficient evidence to suggest that the populations from which these samples were drawn have equal variances?
		.01 depending on the level of significance set by the researcher Controlled by adjusting the level of significance under which the analyses are
	www.happyhtml.com /?q=level-of-significance (227 words)

	Statistical significance (Site not responding. Last check: 2007-11-07)
		More precisely, in traditional frequentist statistical hypothesis testing, thesignificance level of a test is the maximum probability ofaccidentally rejecting a true null hypothesis (a decisionknown as a Type I error).
		So a resultwhich is "significant at the 1% level" is more significant than a result which is "significant at the 5% level".
		However a testat the 1% level is more likely to have a Type II error than a test at the5% level, and so will have less statistical power.
	www.therfcc.org /statistical-significance-109364.html (248 words)

	Significance Tests / Hypothesis Testing
		Had a 99% CI been used, we would say that the test had been performed at the 0.01 level of significance, that is, the significance level (or simply the level) of the test is the probability of rejecting a hypothesis when it is true.
		The level (or size) of a test is the probability of rejecting the null hypothesis when it is true.
		To illustrate this, suppose we are testing the hypothesis that two population means are equal at the 0.05 level of significance by selecting equal sample sizes from the two populations.
	www.tufts.edu /~gdallal/sigtest.htm (1741 words)

	Statistical Hypothesis Testing
		The probability of the last result is 6.25%, which is greater than the 5% significance value, so a run of four heads is not quite enough evidence to cause us to be suspicious of the coin.
		We reject the null hypothesis at the 5% significance level, and we begin to suspect that the coin is loaded.
		A significance level of 1% or lower might be set in the clinical trials for effectiveness against cancer; a significance level as high as 50% might be set in the teratogenicity tests.
	www.mun.ca /biology/scarr/2900_Hypothesis_testing.htm (790 words)

	PROPHET StatGuide: Glossary
		With a significance level of 0.05, this could be considered as the probability of seeing 20 come up on a 20-sided fair die.
		The power depends on the significance level (alpha-level) of the test, the components of the calculation of the test statistic, and on the specific alternative hypothesis under consideration.
		The significance level (also known as the alpha-level) of a statistical test is the pre-selected probability of (incorrectly) rejecting the null hypothesis when it is in fact true.
	www.basic.northwestern.edu /statguidefiles/sg_glos.html (7880 words)

	Rural Public Transportation Technologies: User Needs and Applications FR1-798 (Site not responding. Last check: 2007-11-07)
		The choice of a 10-percent significance level (or a 90-percent confidence level) reflects a moderately restrictive approach in the selection of independent variables that might significantly contribute to the variability in accidents.
		In the model for fatal and injury accidents, none of the variables that were not statistically significant at the 10-percent significance level would have been significant at the 20-percent level.
		The significance of the interaction between ramp type and ramp configuration indicates that each combination of ramp type and ramp configuration has a unique effect on accident frequency that cannot be adequately explained by separate ramp type and ramp configuration effects.
	www.tfhrc.gov /97-106/ch05/ch05.htm (9208 words)

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