Do celebrities die in threes?

Author: Kristian Lum

Elizabeth Taylor in Cleopatra, 1963.

Just a few days ago on March 23, 2011, Elizabeth Taylor died at the age of 79. As news outlets filled with tributes and slideshows about “the last star", one noticeable quote from another big name in entertainment made it into the news. Speaking on behalf of Zsa Zsa Gabor, Prince Frederic von Anhalt said on behalf of his wife: “Over the years, famous people always die in threes and she said, `Well, it's me now.'"

Wait a second. What?? As ridiculous as that sounds, Zsa Zsa is not the only one who seems to think that celebrities die in threes. It seems like every time two celebrities die, there is speculation about who will be the third, as though two celebrity deaths necessarily means a third is on its way. The last time the internets were a-twitter with talk of this superstition was June of 2009, when Michael Jackson and Farrah Fawcett died on the same day, the 25th. Depending on whether you prefer sweepstakes or OxiClean, this supposed death troika was rounded out by Ed McMahon (the 23rd) or Billy Mays (the 28th).

As a statistician (or mathbuster), what I'd really like to do to test this dying in threes hypothesis. In order to do any sort of testing, we have to define what it means to “die in threes." Seriously, what does that mean? It isn't enough that they die in clusters of any size. No, the superstition is specifically that they die in groups of three.

What I propose as a definition of this is that for any three deaths to count as a triple, the time from the first death to the last death in this set must be less than or equal to the time elapsed from the last event prior to the triple, and it must also be less than or equal to the time until the next death succeeding the triple. The three deaths have to be separated in time from the other deaths. For example, let's consider the {Ed, Michael, Farrah} candidate triple, in which case the time from the first (Ed) to the last (Michael and Farrah.. I'm only counting this down to a resolution of one day) is two days. In order for this to count as a triple, no celebrities could have died within one day of either end of this triple, there must not have been any celebrity deaths on the 22nd or the 26th. In order for the Michael, Farrah, Billy candidate triple to be a triple by this definition, no other celebrities would have died from the 23rd until the 30th.

Check out purple line on the left in the plot above, which shows the arrangement throughout the year of the dates of death of some of the celebrities who died in 2009. It does look like the deaths are bunched together. Then look to the right. Those are randomly generated death dates, which, because human brains like to see patterns, also look like there is some clustering.

I calculated that there were 28 triples by my above definition in this data set of the 157 celebrity deaths of 2009. I then randomly generated 10,000 sets of 157 death dates, where the dates are randomly selected over the course of the entire year. I calculated the number of triples in each of these completely random data sets.

This histogram of the number of triples from each of the randomly generated death dates shows (1) a remarkably normal shape and (2) that 28 triples is a totally reasonable number to have seen if celebrities die at random throughout the year.

The number of triples last year (the pink line) falls in about the 70th percentile of what we would expect under completely random death dates – far from anything anyone would consider statistical significance. We would expect to see this number of clusters under complete randomness.

So, hang in there, Zsa Zsa.