Significance Test Cutoff: Is .05 Result Significant?

In summary, the significance level for a result in any significance test is determined by whether it is greater than, less than, or equal to the cutoff value. A value greater than the cutoff is not significant, a value less than the cutoff is significant, and a value equal to the cutoff depends on the specific criteria set by journals and regulatory agencies. In most cases, a two-sided alpha of p=0.05 is required, with a significance level of p=0.025 in each tail. However, there are instances where more stringent criteria are used.
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BigPappa
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In any significance test, if the result is greater than the cutoff it is not significant, if the result is less than the cutoff it is significant. What if it is exactly equal to the cutoff (.05) is it significant or not?
 
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BigPappa said:
In any significance test, if the result is greater than the cutoff it is not significant, if the result is less than the cutoff it is significant. What if it is exactly equal to the cutoff (.05) is it significant or not?

Significance levels are really matters of choice and convention. As far as the matter of whether alpha is an open or closed upper bounded interval; I'm not aware of any general rule. For most research in which I've been involved, journals and regulatory agencies require a two sided alpha of p=0.05 which means p=0.025 is the significance level in each tail. A value in the closed upper bounded interval of alpha=0.025 in the right tail is considered significant for rejecting the null hypothesis in typical cases. However there are many cases where more stringent criteria are set.

(A closed bound includes the bounding value, so a right sided value of exactly p=0.025 would be significant given that alpha level. In practice, I've never seen the issue come up because the alpha cut off is a point on a continuum and therefore an exact value occurs with probability zero).
 
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1. What is the significance test cutoff of .05?

The significance test cutoff of .05, also known as the alpha level, is a commonly used threshold in statistical hypothesis testing. It represents the probability of obtaining a result at least as extreme as the one observed, assuming that the null hypothesis is true. In other words, if the p-value is equal to or less than .05, it is considered statistically significant and the null hypothesis can be rejected.

2. Why is .05 commonly used as the significance test cutoff?

.05 is considered a standard and widely accepted cutoff for statistical significance. It provides a balance between minimizing the likelihood of a Type I error (rejecting the null hypothesis when it is actually true) and maximizing the power of the test (detecting a true effect when it exists). However, the choice of significance level ultimately depends on the specific research question and context.

3. What does it mean if a result is statistically significant at the .05 level?

If a result is statistically significant at the .05 level, it means that the probability of obtaining the observed result by chance alone is less than or equal to .05. This suggests that there is a low likelihood that the observed effect is due to random variation and provides evidence in support of the alternative hypothesis.

4. Can a result be significant at a level other than .05?

Yes, a result can be significant at a level other than .05. The significance level can be adjusted to be more or less strict, depending on the research question and the amount of acceptable risk for Type I and Type II errors. For example, a more stringent significance level of .01 may be used for studies with high stakes or when the sample size is small.

5. What should be considered when interpreting a result that is significant at the .05 level?

When interpreting a result that is significant at the .05 level, it is important to consider the context of the study, the strength of the effect, and the potential for other factors to influence the results. It is also important to keep in mind that statistical significance does not necessarily equate to practical or meaningful significance. Further analysis and replication of the study may be needed to fully understand the implications of a significant result.

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