DALLAS -- Airlines are getting better at sticking to their schedules and are losing fewer bags. Their customers seem to be complaining less often.

on U.S. airlines' quality released Monday by researchers at Wichita State University and Embry-Riddle Aeronautical University.

Many passengers may have trouble believing those conclusions, however.

In just the last few days Delta Air Lines suffered a multi-day meltdown -- cancelling more than 3,000 flights after a one-day storm in Atlanta. And on Monday, United Airlines was in the spotlight after a video showed security agents dragging a man off a plane; he had refused to give up his seat on a flight that United overbooked.

"People don't look at the numbers," admitted Dean Headley, a marketing professor at Wichita State and co-author of Monday's report. "They just know what happened to them, or they hear what happened to other people."

The researchers used information compiled by the U.S. Department of Transportation to rate the airlines for on-time performance, baggage handling, bumping passengers off oversold flights, and complaints filed with the government.

They judged Alaska Airlines to be the best U.S. carrier, followed closely by Delta. Frontier Airlines ranked last, followed by another discount carrier, Spirit Airlines.

The report's general observations:

ON TIME PERFORMANCE: The percentage of flights that arrived on time or close to it rose to 81.4 per cent in 2016 from 79.9 per cent in 2015. Of 12 leading U.S. carriers, only American, JetBlue and Virgin America got worse.

LOST BAGS: The rate of bags being lost, stolen or delayed fell 17 per cent.

BUMPING PASSENGERS: Your chances of getting bumped by the airline dropped 18 per cent, which doesn't include people who voluntarily gave up their seat for money or a travel voucher.

FEWER COMPLAINTS: The rate of complaints filed with the government dropped about one-fifth, with complaints rising only for Hawaiian and Virgin America.

The official complaint rates don't include the larger number of complaints that passengers file directly with the airline. The airlines are not required to report those figures.

The Wichita State and Embry-Riddle researchers have been issuing their report for more than 25 years, making it useful for comparing airlines. But some observers of the airline industry dismiss their number-crunching approach, and there are many other surveys that purport to rank the airlines.

The Transportation Department counts a flight as being on time even if it arrives up to 14 minutes late. "Airlines are happy with that (grace period) because it makes them look better and misleads the passenger," said aviation consultant Michael Baiada. He said airlines can do better, and besides, travellers pay to be on time -- not 14 minutes late.

More broadly, a statistical analysis of government data "really doesn't take into consideration how the customer is treated," said Bryan Saltzburg, an executive with travel site TripAdvisor LLC. "How comfortable are they on the plane? How helpful is the staff? What's the value for what the customer paid?"

TripAdvisor released its own airline rankings Monday, which it said were based on analysis of "hundreds of thousands" of reviews posted by users. It placed JetBlue and Alaska Airlines among the top 10 in the world, and it rated Delta ahead of American and United among the largest U.S. carriers.

Other outfits including J.D. Power and Skytrax also put out ratings. Airlines boast when they win. Recently, American Airlines started putting stickers on all 968 of its planes to note that a trade publication, Air Transport World, named it airline of the year.