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Yves Peirsman

Crazy about Natural Language Processing.

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This September 20 years ago, the first episode of Friends aired on NBC. The sitcom became a world-wide success, and even 20 years later it is still amazingly popular. Jimmy Kimmel made our toes curl when he brought together Rachel, Monica and Phoebe in his show, someone recreated Friends in The Sims 4, and next week a replica of Central Perk will pop up in New York. Inspired by the various seemingly random rankings of Friends episodes, I wanted to find the happiest and saddest episodes of the series. After all, when I watch Friends, it’s these emotions that I’m looking for.

One way to tap into people’s emotions is to analyze their language. Sentiment analysis is an application of Natural Language Processing that automatically measures the positive or negative sentiment in a text. I therefore downloaded the English subtitles of all episodes of Friends, and used the Pattern software to measure the sentiment in each sentence. Pattern assigns a sentiment score between -1 and 1 to each sentence, where -1 is most negative and 1 is most positive. For example, the sentence I’m so happy today gets a score of 0.8, whereas I’m feeling sad gets -0.5. Most factual sentences receive a score of 0, because they do not contain any positive or negative emotion. For every episode, I counted up the sentiment scores of all sentences and divided the result by the number of sentences. This gave me a mean sentiment score, and a measure of how positive or negative the episode is. I then did the same for the ten seasons of the series.

The graph below shows these mean sentiment scores for all ten seasons of Friends. On average, episodes are slightly more positive than negative, with a typical sentiment score between 0.05 and 0.07. Their tone also appears to have become more positive through the years: the language in the last five seasons is consistently more positive than that in the first five. The first season is the least positive one, the last season brought the happy ending that everyone was waiting for:

If we zoom in on the individual episodes in every season, we can see their sentiment scores are all over the place. The graph below has all episodes in a season (typically 24) on the X axis, and their sentiment score on the Y axis. Each season has a different color. For what it’s worth, episode 22, near the end of each season, appears to have the widest variation in sentiment. Immediately after that, most seasons end in a balance of emotions, with very little variation between episodes 23 and 24 across the seasons:

Let’s take a look at the single episodes that stand out. If we focus on the negative emotions, The One with the Screamer is the champion. Joey’s play gets terrible reviews, his new girlfriend moves to LA, Rachel is dating a guy with temper tantrums (despite Ross telling her not to) and Phoebe calls a support line where no one answers the phone. Life is sad indeed. The same goes for the second episode on the list. Joey’s big breakthrough movie turns out to be a disappointment, Rachel freaks out because she has to take eyedrops, and Phoebe is mad at Ross for reasons even she doesn’t know. You get the picture. Here is the full top 10 of negative episodes:

At the other end of the spectrum, the most positive language can be found in The One where Ross got High: Monica and Rachel throw a Thanksgiving party, Chandler tries to charm Monica’s parents, and everyone pretends Rachel’s dessert is delicious, although it is really a mixture of trifle and Shepherd’s pie. Positive language, it turns out, isn’t always sincere. The One with the Worst Best Man Ever is equally ambiguous: Chandler is jealous when Ross picks Joey as his best man, Joey loses Ross’s wedding ring, and Phoebe’s pregnancy causes mood swings. However, these negative feelings are more than compensated by an abundance of positive emotions: Phoebe’s highs, Ross’s thankfulness for his bachelor party, and the happy ending when the wedding ring is recovered and Ross chooses both Joey and Chandler as his best men. It's clear: no Friends episode has positive emotions only — that would make for boring television. Still, these ten episodes stand out:

Friends is a bit like real life. It’s never all good, never all bad. Sometimes people are sincere, sometimes they are not. This makes it hard to always measure emotions correctly, and now and then the algorithm gets a sentence completely wrong. That’s a bit like real life, too. Still, when you compare the results above with the actual episodes, they do make sense. They can help you choose what episodes to watch when you want to wallow in other people’s misfortune, or simply need the comfort that everything will turn out fine. Isn’t that what friends are for?