type 1 error rate alpha error false positive rate STATO:0000053 WEB: http://www.uptodate.com/contents/glossary-of-common-biostatistical-and-epidemiological-terms Yongqun He A quantitative confidence value that refers to the probability of incorrectly concluding that there is a statistically significant difference in a dataset. Alpha is the number after a p-value. Thus, a statistically significant difference reported as p<0.05 means that there is less than a 5 percent chance that the difference could have occurred by chance. quantitative confidence value