What’s the probability that a candidate will have exactly your tech stack at their previous job for a web developer position?
Assuming an even distribution: (I know, a horrible assumption)
- Let’s say you are looking at only three options: AWS, Google Cloud, and Microsoft Azure. There are more options than this.
- Your web server likely runs either Apache or Nginx.
- The 5 most popular JavaScript frameworks: React, Express, Angular, Vue, and Next.js. There are many more.
- You have multiple choices for your database. Let’s stick with Oracle, Microsoft, MySQL, Postgres, and MongoDB. There are many more.
- Your server is either Windows or Linux.
- Your server has a 50% chance of using Python for automation.
3*2*5*2*2*5=600
Hence, the probability that two companies share identical web infrastructure is less than 0.5%!
So don’t obsess over specifics. Doing so almost guarantees you won’t find your candidate.
Let’s recalculate on popularity, since this assumes an even distribution, which is a terrible assumption.
Calculation 2
Even if you used the most common JavaScript framework, ReactJS is at 35.9%, and numbers vary widely on whether Oracle, MySQL, or PostgreSQL are the most used frameworks. Let’s say whatever the most popular framework is, it also has a 30% market share. 30% squared is 9%, so out of 100 candidates, only 9 will have used your database infrastructure and JavaScript framework at their last position!
Then divide by four, assuming an even distribution of Amazon vs. Microsoft vs. Google vs. other, giving us 2.5%.
Then divide by two on whether they are more experienced with Apache vs. Nginx, meaning only 1.25% of candidates will have your particular stack.
Divide that by 4 for Windows vs. Linux and Python vs. no Python. We are down to 0.3125%.
But this is not realistic. Linux controls 90% of the server market, and since you are not a technical person, you have insisted that your company uses Windows as its server because it’s familiar to you. So 1.25% / 10 = 0.125%. Linux puts you at 1.125%.
If you are running the most popular choice, you will need at least 355 candidates to have a chance to find only one candidate who used an identical tech stack to yours at their last job.
Stack Overflow data
Stack Overflow runs a survey every year asking about the stacks used by each developer. Let’s do one final calculation.
- 64.6% of developers have used JavaScript
- 54.1% of developers have used SQL
- 46.9% of developers have used Python.
Assuming these are independent (I excluded HTML because if you use JavaScript, you will have to use HTML), we are looking at 16% of professional developers who have used all three in the last year.
Of the 54.1% of developers who have used SQL, 48.7% use PostgreSQL, bringing us down to only 8% of developers.
52% of these developers use AWS, bringing us down to 4% of developers.
40% of those developers use Node.js as their JavaScript framework, bringing us down to 1.6% of developers.
53% of those developers use Docker, bringing us down to 0.8% of developers
Only 51% of those developers use Jira, bringing us down to 0.4% of developers.
Only 59% of those developers use Windows on their personal computer, bringing us down to 0.2% of developers.
So, in order to find this web developer who uses JavaScript, PostgreSQL, Python, AWS, Node.js, Docker, Jira, and Windows (because I’ve seen job descriptions, they literally ask if you have experience in Jira and Windows FML), you will need to interview around 500 developers.
Finding a candidate who matched your current tech stack at their last company is unrealistic. Let alone the years of experience requirements for every skill! If you require many years of experience in every tech your company uses, you will never find your candidate.
Focus on transferable skills for success.
A reasonable search
As we have explored, there are many tech stacks, and it’s highly unlikely that any two applicants to your job used exactly the same tech stack at their last company.
Pick no more than 3 technologies as must-haves. You need to have these three skills to be hired. For these three, find the ones that take the most time to learn and have few close alternatives.
So if I were hiring for a web developer position:
- JavaScript (64%)
- Linux (21%)
- SQL (54%)
You need knowledge of these three technologies otherwise, we will not hire you. We are running a web application, we use JavaScript, Linux, and SQL, which is the most common web stack. 7% of developers likely have these three skills according to StackOverflow’s data. 93% of professional developers who responded to Stack Overflow’s survey are out of the scope for our position.
Now for the nice-to-haves. Pick up to three of these.
- AWS (52%)
- Node.js (40%)
- Docker (53%)
So we are already down to only 7% of our applicants from our must-haves. In order to find someone with these three skills as well we are now down to around 0.8% of candidates.
With only 6 skills, we will now likely have to interview over 100 candidates to find our candidate, all of whom will accept the job if offered. Otherwise the number of necessary interviews increases rapidly.
If I had to drop one of these requirements, I would drop AWS. The technical difference between AWS vs. other server positions is far smaller than someone who used a different JavaScript framework, and someone who does not know docker. Now we have a chance of finding a candidate out of fewer than 100 candidates. The learning curve for AWS is shallow compared to the others, and as long as you have experience deploying servers in the past, which you do because you have experience with Linux, AWS is the least important of these three nice-to-haves.
If I had to pick prioritization between Node.js and Docker, I would prioritize Docker and ensure the person has experience using virtualization, either Docker or Kubernetes. So, adding only Docker to our list of three essential skills as our top priority of nice to haves, we now have a chance of finding our candidate out of 30 candidates.
Now we are looking at a realistic job search with 30 interviews, where one of our candidates will likely have experience in JavaScript, Linux, SQL, and virtualization.
Also, this is the tech stack where you will have the most qualified applicants. Any other stack you design will have fewer matches!
We haven’t even gotten into the years of experience requirements.
This is why you will never find your candidate by using typical hiring practices.
This is how tech hiring needs to change.