A lonely bastion of optimism and altruism on the Internet, the subreddit Random Acts of Pizza allows users to fulfill one another’s wishes for a free pie. The site works by allowing people to post messages asking for pizza, which others can then grant if they find the post compelling.

Now, researchers at Stanford University have released a study that examines why certain pizza requests get fulfilled and others do not, and can even predict whether a request will be fulfilled with 70 percent accuracy.

In How to Ask for a Favor:  A case study on the Success of Altruistic Requests, Tim Althoff, Cristian Danescu-Niculescu-Mizil, and Dan Jurafsky analyzed more than 21,000 posts that appeared on Random Acts of Pizza between December 2010 and September 2013. According to MIT’s Technology Review, the researchers looked at how certain features might be responsible for the success of a post, the similarity of the requester to the benefactor, and whether the post “contained evidence of need in the form of a narrative that described why the requester needed free pizza.”

The researchers fed the data through a standard machine-learning algorithm and found that clearly communicating need through the narrative was essential to getting a pizza request fulfilled. Indications of “gratitude, evidentiality, and generalized reciprocity, as well as high status of the asker further increase the likelihood of success” the study found.

Once all the data had been processed, the algorithm correctly predicted whether a pizza request had been fulfilled 70 percent of the time. There is no word yet on whether the researchers have taken advantage of their findings to score free pizza.