Constrained simultaneous CI for μᵢ − best of the others; always contains 0 at one end.
One-sided Dunnett critical value used for this group's intervals.
ȳᵢ − best of the others (max for 'largest', min for 'smallest').
The interval shows μᵢ beats every other group (the zero end is the other side).
The interval leaves room for μᵢ to be the best (upper > 0 for 'largest', lower < 0 for 'smallest').