You are trying to measure what?
I'm going to assume your answer is "on the job performance". If not, this is going to be a difficult conversation, and I'd ask why you are trying to measure for something you aren't going to be paying for.
The best predictor of on the job performance is ... on the job performance. Everyone but the most junior person has experience. Look at that.
All of these exam type questions usually rely on knowing a trick, or being recently well versed. I TA'd a graduate course in Algorithms. That's rather relevant, I would think, since you aren't offered that if you don't have ability. Yet you know the last time I've done, say, dynamic programming? It's been awhile. I know about it, I know when to decide whether to pull it out, but ask me to do it, in a high pressure interview (all interviews are high pressure), and well, I'll probably fail. I'm working on other things like Bayesian inference. Bet you'd fail doing that stuff, even though it is just simple multiplications and such, when you get down to the implementation. Unless, of course, you are working on that sort of stuff right now.
I find the situation in SV somewhat ridiculous. To go out and interview means a lot of prep. Google recommends spending a month reviewing algorithms before applying. You know, I have an actual job, and I have open source side projects, and I have a family, and hobbies, and an old dog I want to spend all my time with. It is trivial to find out my skills by looking at what I have done and asking me questions about it. Have me give you a 1-2 hour tech talk, for example (I like public speaking, most don't so that is not a universal solution). Have me write some code with you, if you must. I work at a very high level, but I am not necessarily 'clever' at seeing the right trick in 10 seconds under pressure in an interview.
Also, how important is that sort of thing, really? For some jobs it is, undoubtedly. If you want me to write a load balancer for your cloud infrastructure, there are some algorithms I need to understand. Even then, not knowing something now is not evidence I can't do the job. I can learn - it's how I've done everything up to now. I can learn your thing too. More importantly (to my mind) - am I a hard worker? Can I mentor others? Can I lead a team? Can I put a schedule together, and recognize when that is appropriate and not appropriate? Can I make a budget? Can I talk to clients? Do I meet my deadlines? Do I solve problems - not implement the cards in this sprint - but see friction of some sort at work and engineer a solution? Do my peers like working with me? Do I get shit done? Is my code maintainable, readable, modular, commented? Can I write? Can I teach? Can I work with the CEO?
I've been to so many interviews where they don't even try to learn any of that latter stuff, where they show no interest in what I have done, where they don't try to figure out if I can do the actual job they are doing, but are deeply interested in if I can program a smart pointer, from scratch, to some arbitrary set of requirements. It is all just deeply puzzling to me.