What’s the hardest question you get asked in a job interview for a software developer position? My beautiful wife can attest that I am self-deprecating to a fault in interviews, but in particular, I tend to get hung up when people ask me to rate myself at a certain skill, e.g., “How good are you at estimation, from 1-10?“. It’s a tough question because anything above 7 implies I think I am some sort of recognized expert, while anything below could be interpreted the other way, as if I had merely read a blog post on the subject and would like to try it some day. The answer is important, because interviewers can use this question to detect resume embellishments and overconfidence, two dangerous traits in a candidate.

I recently had an opportunity to examine the problem of evaluating software developers’ experience, and in my research I found a great answer on StackExchange.com that really resonated with me. I paraphrased and adapted the following categories of software developer experience from the original post by Chuck Conway, which may be referenced at http://programmers.stackexchange.com/a/173107. These categories of experience are also loosely informed by the Programmer Competency Matrix by Sijin Joseph. The following labels are intended to be granular enough to apply to individual skills, tools, languages, etc. in isolation, but may also be applied in aggregate to a developer’s set of primary skills to get an idea of their overall experience.

Without further ado, I submit categories of software developer experience, on a scale of 1 to 10:

Mastery, 7.5 – 10: The developer is an expert in the field, capable of advancing the state of the art and speaking with authority on the subject. The developer possesses deep knowledge of library / language source code and design decisions behind it. The developer may have contributed to the development of the subject and/or may have written on the subject at length.

Proficiency, 5 – 7.5: The developer has multiple projects’ worth of professional experience in the subject and has in-depth first-hand knowledge in design, implementation, and support. The developer knows best practices and understands the motivating factors behind them. The developer is aware of historical, current and future developments in the field. The developer has some knowledge of the underlying implementation details and how it can affect usage. The developer is most likely used to being the most experienced person in their team / organization in this subject, and is comfortable teaching and supervising others in its use and application.

Competency, 2.5 – 5: The developer has experience practicing the subject independently in a professional role. The developer has some awareness of best practices and guiding design principles, and can apply them correctly in most situations. The developer can independently execute support and implementation tasks, but may benefit from some sort of review / supervision process for new design work. The developer is probably most comfortable developing individual components in isolation.

Foundational Ability, 1 – 2.5: The developer has some basic exposure to the subject, either through academic projects or through limited professional work. The developer is not yet skilled at applying the solution to a variety of problems. The developer is not aware of best practices and may contribute to technical debt if not supervised. This developer has the potential to grow and become competent, but needs both oversight and guidance in order to get there.