Each bar is how the fare moves with one route attribute when the others are held constant. Fares in this fit are also lower on busier routes and on more concentrated ones.
What this shows: The vertical axis shows Coefficient (log-linear).
Conditions and method
Status: descriptive (a pattern in the data, not a causal estimate).
The bars are in a fixed order and are not ranked by size.
The “Unrestricted-fare-basis share (F/C/D)” regressor is the share of coupons on unrestricted or high-fare fare bases, a code each carrier defines. It stands in for fare restrictions, and its positive coefficient is an association with those restrictions, not a price premium for the first cabin.