The Simpsons broke Gunsmoke‘s record as primetime television’s longest running scripted series in history in 2018, and this fall the show began its 30th (30th!) season. After three decades of winning ratings and acclaim hardcore, fans agree on two things about Springfield, U.S.A.’s most beloved family: the show is the best ever, even though it’s been the worst for far longer. When did the split between excellence and incompetence take place? What was the exact moment the show lost it? Viewers might never agree on the exact moment things went sideways, but science might have the answer.

On today’s Nerdist News, host Jessica Chobot explains how a detailed research paper from PhD student Nathan Cunningham used a combination of the IMDb scores and the writers responsible for each episode to graph when the show began the slide fans have been complaining about for almost twenty years. Did it come even earlier when the original writers left the show, or later when the series stopped being about the family and started focusing on silly premises? Or was it a specific episode, like when Frank Grimes bit the big one or Seymour Skinner turned out to be a fraud? Or can the split in quality be found during a well-defined break?

Science! Though that answer checks out, viewers will still say another moment is the exact-exact moment. Because if there’s anything fans of The Simpsons love more than the first decade of the show, it’s arguing about when it got bad.

What do you think? When did the show stop being the best? Don’t be the worst. Tell us your answer in the comments below.