null hypothesis

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Related to null hypotheses: Alternative hypothesis, P value

null hypothesis

[′nəl hī′päth·ə·səs]
(statistics)
The hypothesis that there is no validity to the specific claim that two variations (treatments) of the same thing can be distinguished by a specific procedure.

null hypothesis

a working hypothesis which states that there will be no statistically significant difference between the EXPERIMENTAL GROUP and CONTROL GROUP.

When an experiment is set up, or observational data collected, this is designed to test a HYPOTHESIS, or theory which has been developed from previous work. This is the EXPERIMENTAL HYPOTHESIS, and it states what the expected difference is between the groups if the theory is correct. The converse hypothesis is also conventionally stated: this is the null hypothesis, that predictions from the theory are incorrect, and there is no difference between the groups in the VARIABLE investigated. See also INDEPENDENT VARIABLE, DEPENDENT VARIABLE.

References in periodicals archive ?
The evaluation of DM intake estimates described on Table 1, points out the non-rejection of both null hypotheses (p>0.
The following null hypotheses are tested in the context of a VAR model to determine a causal relationship between stock prices and fiscal and monetary policies:
This was achieved by inverting the acceptance region of the likelihood ratio statistic under a sequence of null hypotheses that restrict the values of the half-life or impulse-response to a shock.
Our results for the standard model are reported in Table 1, which presents the p-values, test statistics, and degrees of freedom for Wald tests for five null hypotheses of interest: (1) the coefficients on positive monetary shocks are jointly equal to zero; (2) the coefficients on positive monetary shocks sum to zero; (3) the coefficients on negative monetary shocks are jointly equal to zero; (4) the coefficients on negative monetary shocks sum to zero; and (5) the sum of the coefficients on positive and negative monetary shocks equal one another, that is, money supply shocks are symmetric in their effect on output.
We tested the null hypotheses that (1) MA would produce no developmental malformations similar to those produced by the positive control, retinoic acid (RA) and (2) the degree of vulnerability to treatment would not differ between embryos and hatchlings.
The results were found to be not significant, therefore the null hypotheses for both phases of the study were supported.
To explore the purpose of this study in a systematic way, the following null hypotheses were tested:
Null hypotheses that MCOs' contracting choices were random with respect to the information published in the Cardiac Surgery Reports were tested.
Null hypotheses are reference points against which alternatives should be contrasted.
Hence this paper contains tests of both null hypotheses and shows that frequently neither is rejected for monthly data from five major industrialized countries.
A five-way analysis of variance (ANOVA) was conducted, testing the null hypotheses that in each of the five job description areas, the population of students would have the same average score regardless of the sentence used in the job description.