Art by Daniela Gomez

I’m no statistician, but I’d wager that the majority of UC Santa Barbara students have experienced a case (or many) of the mysteriously disappearing sock due perhaps to faulty dorm laundry machines or the common I.V. raccoon. Luckily for us, scientists have created a mathematical model to predict the likelihood of having an unmatched sock in a load of laundry. After surveying 2,000 people in the UK and conducting detailed interviews, psychologist Dr. Simon Moore and statistician Geoff Ellis found that the main contributors to the missing sock phenomenon were the complexity of a load of laundry and the number of socks per wash cycle.

Moore and Ellis created the following sock loss formula:

Sock loss index = (L+C)-(PA). 

L stands for laundry size, or the number of people in a household multiplied by the number of washes done in a week. C refers to the washing complexity, calculated by the product of the number of types of loads (e.g. darks vs. lights) and the total number of socks washed in a week. P represents the subject’s positivity toward doing laundry on a 1-5 scale of “Strongly dislikes doing laundry” to “Strongly enjoys doing laundry.” Finally, A refers to attention, a quality calculated by the sum of the following actions done prior to each wash: checking pockets, uncuffing sleeves, turning clothes inside out or right side out, as per instructions, and unrolling socks. The higher the sock loss index, the higher the probability is of losing socks. 

The scientists even worked out a formula for the probability of losing a sock in a particular week, as follows:

Probability of sock loss = 0.38+(0.005L)+(0.0012C)-(0.0159 PA)^3

In addition to statistical modeling, the interviews conducted in the UK found four primary psychological explanations for sock loss during the laundry process. The first is the simple assumption that someone else will take responsibility for making sure all the socks to be washed are paired correctly. The second is heuristics, or the tendency for us to be satisfied with a cursory check for a lost item instead of doing a complete or exhaustive search. Another element is confirmation bias. Confirmation bias is the tendency to interpret, identify or recall information in a way that supports one’s existing beliefs or assumptions. In the case of doing laundry, confirmation bias manifests in the assumption that if there aren’t any visible odd socks, the laundry will not contain any odd socks at all. Finally, simple human error can contribute to many lost or unpaired items in the laundry. For example, smaller items can fall behind or between washing machines, or they could be forgotten in the machine during the unloading process. 

Ultimately, this study cannot tell you who or what absconded with the sock you left in the wash, since there are too many human variables to condense into a single formula. Nevertheless, it can definitely help you prepare your laundry so you won’t start the day on the wrong foot — or sock!