In our life we have to face dozens of choices: from the simplest, how to decide whether to try looking parking in the center on Saturday evening or settle for a distant place and walk a little, up to the choices that condition our long -term happiness, how to choose a Work or a partner. How do we understand When is the right time For stop looking And finally make a decision? The best possible strategy to make the right choice is the “Rule of 37%“. This rule suggests reject any option during First 37% available possibilities and then select there First subsequent option that results improve of all those previously seen. This strategy guarantees us that, if there are many options to choose from, we will be able to find the best with 37% probability. This means that with 63% probability we will never find the perfect parking, the work of our dreams, the love of our life. Still, it’s the best strategy we have.
Let’s see more in detail how and why the “Rule of 37%”.
The problem of optimal interruption: how to choose if I don’t know the options?
Let’s imagine we are at research of a place of Work. After each interview we do, we must decide immediately if accept work o reject To wait for a potentially better option. The problem is that, once a job was rejected, we cannot go backbecause someone else will be taken shortly thereafter. Clearly, we would like to be able to choose the best job, but how can we do if we can’t see all the options? As further difficulty, we do not have a numerical criterion and objective with which to give a score to each work (for example: we do not use the RAL- gross annual salary- as the only measure to understand if we are interested in a job), but we can order the various jobs Based on our preference (so we can evaluate how interesting a job for us).
So, how to establish whether to accept or not, if we still don’t know what other jobs will present themselves in front of us and how to evaluate them?
Find a balance between information and the possibility to choose
To understand what the best strategy is, let’s start with the simplest case: if we have a single interview of work and we are unemployed, we have to satisfy ourselves and choose that job. If we have Two interviewson the other hand, we have the 50% of the possibility of choosing the best work between the two. With three interviews, the situation becomes more interesting: if we chose a job random we would have one out of three (33%) to choose the best job for us, but if we use a little strategy our probability improve. In this case, it all depends on the second interview. When we go to first interviewwe cannot establish if this is the best job because we cannot compare it With the next two: either we choose it immediately or go on. When we go tolast interviewwe have All information that we need, but we have no Possibility of choicewe must necessarily accept that job because we cannot go back. But when we present ourselves to second interview we have both the possibility to choose both the comparison with the previous interview.
In short, in first interview We have no meter of comparison But we have the opportunity to choose the work or not because we know that if we refuse we have two other interviews in front of us. On the contrary in the third interview We can compare the proposal with the previous two and we have a complete picture of the situation, but We have no more choice Because if we refuse, now all the possibilities have gone. In both options, there is an imbalance between information and choice.
And for the Second interview? Here the situation becomes more interesting: we are able to compare it at least with another option, that is, the first interview we have already made, and we also have the opportunity to choose. In fact, if we decide to refuse it, we certainly do not stay out of work but there will be the third interview to give us another possibility.
So what happens if We choose the second job only if it is better than the firstbut it we refuse and we choose the third If it is not?
Observing for a while, then choosing “the best remaining” is the best possible strategy
We call our possible works A, B and C, where TO is the best possible workB the mediocre one and the worst. These interviews can take place in six different orders: ABC, ACB, BCA, BAC, CAB, CBA.
The strategy of looking at the first interview and then choosing any job is better than the first, that is, all those cases in which after evaluating the first interview, we choose the second only if it is better than the first, if not we move on to the third, would have Success – that is, the choice of the best work A – in three out of six cases, Meaning what:
- B-TO-C in which after evaluating B we move on to the second interview A, which being better than B will be chosen
- Bc-TO in which after evaluating B, we discard because worse than B and thus we come to choose the third work A, better both of B and C
- C-TO-B in which after evaluating B, we choose to be better than C.
Likewise, the tactic would bring to bankruptcy in three other Cases:
- In two cases where the best choice A, it happens first and therefore is discarded (CAc-B)
- And the case in which the first choice is the worst C and the second is the mediocre B, which according to the strategy requires to accept B without considering a (c-B-TO)
We would therefore be able to get the best job 50% Of times, that is 3 times out of 6. A clear improvement compared to the random strategy, which guaranteed me success only 33% of the time.
This method works well with 3 interviews, but what happens with 4? If we apply the same reasoning and make some more calculations, we discover that in the case of 4 possible choices we are successful only in 11 out of 24 cases, that is 46%. If, on the other hand, the interviews are 5, the percentage decreases further reaching 43% of success cases.
This makes us understand that as the number of options increase, the probability of success. But not forever! There is a limit to this probability, that is, a value of the percentage of success cases under which we will never descend, regardless of how great the number of possible choices has become, and it is precisely 37% from which the name “Rule of 37%”. But how is it possible? Thanks to the concept of convergence. In fact, if we calculate the probability of success of our tactic as the number of choices possible, the function that describes this probability converges, precisely, towards a value of 0.37, that is 37%. To be “more mathematical”, the value of probability converges towards 1/E, Where And It is the number of Euler, whose value is about 2.72 and therefore, considering its inverse (1/E) It is obtained 1/s ≃ 0.37, that is 37%.
All this reasoning works even if we consider the time we want to dedicate to research. So, if in this 2025 we want to change work and we do not have an objective criterion of choice, we discard all the job proposals that reach until mid -May (which, assuming to make a uniform number of interviews per month, corresponds to 37% of the Year) and then we choose the next best offer.
