Epidemics and Viral Trends: The ALS Ice Bucket Challenge
When I think back to the year 2014, many things come to mind. I remember my little sister going to see Disney’s “Frozen” about three hundred times, I remember listening to OneRepublic’s “Counting Stars” every day on the bus to school, and of course, the seemingly endless “ALS Ice Bucket Challenge” posts on my social media feed. The ALS Ice Bucket Challenge has recently made its way back onto headlines with the heartbreaking passing of its founder, Pete Frates, last Wednesday.
The ALS Ice Bucket Challenge took the world by storm. Initially started by Pete Frates, with the help of Pat Quinn and Anthony Senerchia, the challenge sought to raise funds for ALS research. The fundraiser proved to be an outstanding success, raising over $115 million and successfully engaging over 17 million people across the world to take part in the challenge. Surprisingly enough, the success of the fundraiser can largely be explained by the same framework as epidemics.
Disclaimer: I am in no way trying to directly compare a viral challenge that raised an enormous amount of money and did so much good with the negative connotation epidemics have (especially in 2020). I am simply relating them based on the framework for how they spread, not their impacts.
We discussed epidemics as owing their success (or failure) to the branching process model. In short, the model states each node’s neighbors are denoted by k, and the probability of one node passing something to one of its k neighbors is denoted as p. With this, we learned that the simple formula for predicting an epidemic’s success:
R(0) = p * k
We called this R(0) value the basic reproductive number for a pandemic, and learned that if it is greater than 1, the disease, or epidemic, is replenishing itself. Alternatively, if the basic reproductive number is less than 1, the epidemic will not last as long, as it is not replenishing itself. With this in mind, and understanding the two main factors that dictate to what extent an epidemic will spread (p and k), we can use this model with the ALS Ice Bucket Challenge.
The challenge was very simple: if you were tagged by someone in their post, you were supposed to either film a video of you getting a cold bucket of water poured on your head, and/or donate to ALS research. The interesting thing to note is that at the completion of the challenge you were asked to tag three others to participate next. In this same way, we have a very similar model as we’ve discussed with pandemics where “ground zero” was the founder of the challenge, Pete Frates, and the k value is equal to 3. Each person has to tag three others in the way that a person would have k neighbors they’ve come in contact with during an epidemic. See below for a diagram of our Ice Bucket Challenge “epidemic.”
The other variable we need to complete the model is the probability of those tagged to get infected. In this case, we are looking for the probability, p, that each of those tagged will continue the challenge and post themselves doing it. While this number is impossible to calculate in itself, we know that in order for an epidemic to be “successful” in replenishing itself it must observe R(0) > 1. Well, since R(0) = p * k, and we’ve established k as 3, p must have been greater than 1/3 as this challenge took off on a worldwide level, and is still being posted about today, 6 years later. This means that for every person tagged in a post, at least 1 out of every 3 people posted themselves doing the challenge as well, on average, at the height of the challenge. Why is this? There’s a lot of speculation as to what made the challenge so effective, but there are a few main takeaways that explain the high p value. For starters, the “epidemic” had a moral component. It was for a good cause, and it is likely many people wanted to get involved to help out. As one PROVOCO piece put it, “The cause and effect of the challenge were clear and people were able to get behind it without any moral ambiguity.” Furthermore, many celebrities took part in the challenge, encouraging their fans to do so as well. It was a “cool” trend to be a part of in the sense that everybody seemed to be doing it, which likely originally gained traction from the moral component and then exploded as a popular trend with the help of these celebrities. All in all, the ALS Ice Bucket Challenge was a global phenomenon that did a lot of good for a lot of people. By analyzing its spread with the simple epidemic model, we can see why it was so effective.
Sources: http://web.alsa.org/site/PageNavigator/blog_120919.html , https://medium.com/@Provocome/the-success-of-the-ice-bucket-challenge-269f1776122d#:~:text=The%20ice%2Dbucket%20challenge%20was,using%20standard%20fund%2Draising%20techniques.