OPM ran a standard statistical test to determine whether the difference between positive percentages for each comparison is statistically significant. When such a test indicates less than a 5 percent probability that a difference occurred by chance, that difference is considered to be statistically significant, i.e., it is a reliable "significant difference." In these reports, those test results are shown in the report column labeled "Significant Difference" as follows:

an up arrow (Ó) means the increase in positive response percentages over time is statistically significant

a down arrow (Ô) means the decrease in positive response percentages over time is statistically significant

a blank means no statistically significant difference in positive response percentages over time

Finding that a difference between two percentages is statistically significant does not imply the difference is meaningful. Government managers must rely on their substantive understanding of the survey topic to decide whether a statistically significant difference is important.