hypothesis

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hypothesis

[hi-poth´ĕ-sis]
a supposition that appears to explain a group of phenomena and is advanced as a bases for further investigation.
alternative hypothesis the hypothesis that is formulated as an opposite to the null hypothesis in a statistical test.
complex hypothesis a prediction of the relationship between two or more independent variables and two or more dependent variables.
directional hypothesis a statement of the specific nature (direction) of the relationship between two or more variables.
Lyon hypothesis a hypothesis about development of X chromosomes in the embryo; see lyon hypothesis.
Monro-Kellie hypothesis [mun-ro´ kel´e] an explanation of the maintenance of intracranial pressure: The skull is viewed as a closed container housing brain tissue, blood, and cerebrospinal fluid; a change in any of these three components will affect the other two. If the volume added to the cranial vault is equal to the volume displaced, the intracranial volume will not change.
nondirectional hypothesis a statement that a relationship exists between two variables, without predicting the exact nature (direction) of the relationship.
null hypothesis the hyothesis that the effect, relationship, or other manifestation of variables and data under investigation does not exist; an example would be the hypothesis that there is no difference between experimental and control groups in a clinical trial.
hypothesis test the abstract procedure that is the theoretical basis of most statistical tests. A hypothesis test decides between two hypotheses, the null hypothesis (H0) that the effect under investigation does not exist and the alternative hypothesis (H1) that some specified effect does exist, based on the observed value of a test statistic whose sampling distribution is completely determined by H0. The decision is made to reject H0 and by implication to accept H1 when the test statistic falls within a given set of values called the critical region. This region is so determined that the probability of rejecting H0 when it is in fact true (a so-called Type I error, the reporting as significant results that are only the result of random variation and not a real effect), is set at a specified level (symbol α). When this level is set before the data are collected, usually at 0.05 or 0.01, it is called the significance level or α level. It is now more common to report the smallest α at which the null hypothesis can be rejected; this is called the significance probability or P value. The ability of the test to accept a true alternative (and thus to detect a real effect when it exists) is termed the power of the test. Note that no statistical test actually tests the H1.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

hy·poth·e·sis

(hī-poth'ĕ-sis),
A conjecture advanced for heuristic purposes, cast in a form that is amenable to confirmation or refutation by conducting of definable experiments and the critical assembly of empiric data; not to be confused with assumption, postulation, or unfocused speculation.
[G. foundation, assumption fr. hypotithenai, to lay down]
Farlex Partner Medical Dictionary © Farlex 2012

hypothesis

(hī-pŏth′ĭ-sĭs)
n. pl. hypothe·ses (-sēz′)
1. A tentative explanation for an observation, phenomenon, or scientific problem that can be tested by further investigation.
2. Something taken to be true for the purpose of argument or investigation; an assumption.
3. The antecedent of a conditional statement.

hypothesis

Epidemiology A supposition, arrived at from observation or reflection, that leads to refutable predictions; a conjecture cast in a form that will allow it to be tested and refuted
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

hy·poth·e·sis

, pl. hypotheses (hī-poth'ĕ-sis, -sēz)
A conjecture cast in a form that is amenable to confirmation or refutation by experiment and the assembly of data; not to be confused with assumption, postulation, or unfocused speculation.
[G. foundation, assumption fr. hypotithenai, to lay down]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012

hypothesis

A tentative proposition used as a basis for reasoning or experimental research, by means of which it may be rejected or incorporated into accepted knowledge. See NULL HYPOTHESIS.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005

hypothesis

a proposition assumed on the basis of observation which might account for or explain something which is not fully understood. see SCIENTIFIC METHOD.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005

significance

In statistics, an indication that the results of an investigation on a population (e.g. patients) differ from those of another population (e.g. general) by an amount that could not happen by chance alone. This is evaluated by establishing a significance level, that is the probability, called p value, which leads us to reject or accept the null hypothesis Ho (there is no significant difference between two populations and the difference is attributed to chance) and accept or reject the alternative hypothesis H1 that there is a statistically significant difference between two populations. A p value p < 0.05 is often considered significant, but the lower this figure, the stronger the evidence. See randomized controlled trial.
Millodot: Dictionary of Optometry and Visual Science, 7th edition. © 2009 Butterworth-Heinemann

hy·poth·e·sis

, pl. hypotheses (hī-poth'ĕ-sis, -sēz)
A conjecture advanced for heuristic purposes, cast in a form that is amenable to confirmation or refutation by conducting of definable experiments and the critical assembly of empiric data.
[G. foundation, assumption fr. hypotithenai, to lay down]
Medical Dictionary for the Dental Professions © Farlex 2012
References in periodicals archive ?
Another hypothesis, the marginality hypothesis, suggests that institutional discrimination contributes to decreased participation in interpretation.
Regarding the results of table 1 and the score for chi-square test which is 87.342, and also the significance level which is 0 for the chi-square test, with the confidence level of 95 % hypothesis H0 is rejected and hypothesis H1 of the difference in the answers is approved.
Curry also suggests that the desire to reverse the null hypothesis may have the goal of seeking to marginalize the climate skeptic movement, a vocal group that has challenged the scientific orthodoxy on climate change.
Surely, interpretation of clinical trials is more straightforward--can't we simply use the P value to tell us the probability the null hypothesis is true?
It Is a Mistake to Frame an Experimental Project with a Hypothesis Because the Experimentalist Will Filter Data through the Lens of That Hypothesis, Rejecting Contradicting Evidence in Favor of Validating Evidence.
A hypothesis is a possible explanation for a set of observations.
Some climate change skeptics have tried to use this hypothesis to suggest that greenhouse gases may not be the global warming culprits that most scientists agree they are.
Still in typescript, this text contains the lecture notes for a course Cohen (1934-2007) taught at Harvard in spring 1965, shortly after his work on the continuum hypothesis. His main goal was to demonstrate the independence of the hypothesis, but in order to keep the course as self-contained as possible, he included background material in logic and axiomatic set theory as well as Godel's proof of the consistency of the hypothesis.
The usefulness of hypothesis testing methods has long been the
By examining examples taken from the student reports, this study aims at identifying students' problems in understanding the concept of hypothesis formulation and testing.

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