Significant and Significance

If there is any doubt about whether significant/significance refers to statistical significance, clinical significance, or simply something “important” or “noteworthy,” choose another word or include a modifier that removes any ambiguity for the reader.

The AMA Manual of Style (§20.9, Glossary of Statistical Terms, pp 893-894 in print) includes definitions for statistical significance (the testing of the null hypothesis of no difference between groups; a significant result rejects the null hypothesis) and clinical significance (involves a judgment as to whether the risk factor or intervention studied would affect a patient’s outcome enough to make a difference for the patient; may be used interchangeably with clinical importance). Significant and significance also are used in more general contexts to describe worthiness or importance.

Often the context in which the word appears will make the meaning clear:

▪ Statistical Significance:

• Exposure to the health care system was a significant protective factor for exclusive throat carriage of Staphylococcus aureus (odds ratio, 0.67; P = .001).

• Most associations remained statistically significant at the adjusted significance level (P < .125).

▪ Clinical Significance:

• Low creatinine values in patients with connective tissue diseases were found to be clinically significant.

• The combination of erythromycin and carbamazepine represents a clinically significant drug interaction and should be avoided when possible.

▪ Worthy/Important:

• His appointment as chair of the department was a significant victory for those who appreciated his skill in teaching.

• A journal’s 100th anniversary is significant and should be celebrated.

Sometimes, however, the context does not clarify the meaning and ambiguity results.

▪ The one truly significant adverse effect that has caused carbon dioxide resurfacing to lose favor is hypopigmentation, which can be unpredictable and resistant to treatment.

To avoid the possibility of ambiguity, some have recommended confining the word to only one of its meanings. However, why cheat a word of one of its legitimate meanings when there are ways to retain its richness and yet not confuse the reader?—Cheryl Iverson, MA

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