# significance

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## significance

Clinical medicine A finding to be weighed in establishing a diagnosis, or influencing management of, a clinical state, which may be expressed as a finding of significance  Statistics A measure of deviation of data from a statistical mean, defined by a probability–p value, where a p of 0.05 indicates a 5% possibility or 1 chance in 20 that a dataset differs from a mean and 19 chances that it will not. See Clinical significance, Statistical significance.

## significance

(statistics) a description of an observed result that shows sufficient deviation from the result expected to be considered different from the expected result. Significance tests such as the CHI-SQUARED TEST can be carried out to produce a value that is converted into the probability that an observed result will match the result expected from a theory. In biology there is a convention that, if there is more than a 5% chance (P < 5%) that the observed result is the same as the expected, it is possible to conclude that any deviations are ‘not significant’, i.e. have occurred by chance alone. If, however, there is less than a 5% chance (P < 5%) that observed and expected are the same, then it is concluded that the deviations are ‘significant’, i.e. have not occurred by chance alone. For example, tossing a coin 100 times gives 58 heads and 42 tails. The probability that 58:42 is similar to the expected 50:50 is greater than 5%, thus we can conclude that there is no significant deviation between observed and expected results.

## 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.
References in periodicals archive ?
Information on income and percentage share from different economic activities other than dairy production were also analysed to evaluate their significancy to the total household economy.
The "crisis of transition from the unreal to the real" (9.234) as we come to consciousness and our thoughts become reliable, move from chaos to order, occurs as an a priori "re-shaping" of such elementary mental representations, a reinstatement of "fixed relations." De Quincey outlines this creative model of mind lightly and self-deprecatingly in "Sir William Hamilton Bart.": "With this brain, so time-shattered, I must work, in order to give significancy and value to the few facts which I possess--alas!
Similarly, the pupil who would drive an automobile 90 mph over the second mile in order to average 60 mph for two miles after driving the first mile at the rate of 30 mph also manipulates symbols sans significancy.
For number of tillers the significancy between the treatments was observed in the first and the third cuts (table, 2), generally the third cut scored the highest values for number of tillers (table 4).
T- Test was used to show the significancy in Ca concentration in feces at the two period (middle and the end of the experiment) significancy was considered at P [less than or equal to] 0.05 (SAS,1996).

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