Difference of means, group i minus group j.
The group compared (1-based position among the groups compared, i > j).
The group it is compared with (1-based index).
Lower ends of the simultaneous intervals.
Labels of the comparisons, "a-b": the group labels when given, otherwise the positions of the samples in the
list (from 1). Groups without data are left out, as in R.
p-values adjusted for the multiple comparisons.
Alias of pAdj: the same array.
Upper ends.
R's warnings, each once, in R's order (an empty array when there are none).
Result of TukeyHSD: one entry per pair of groups, in R's order (2-1, 3-1, ..., k-1, 3-2, ...).