Let it be no mistakes, I'm not a great interviewer and definitely not an experienced one but I've got really strong opinions about the way interviews should go and the questions "style" that should help you screen your candidates. It's not only "good" .vs. "evil" questions that I want to talk about here. It's the attitude and the fun of the process. Yes, you read it just right: interviews should be FUN.
Money is an interview's killer.
Money is ego. ego turns to hostility. hostility lead to bad questions. bad questions screen the wrong people. bad people is bad code. bad code is no fun. no fun is plain boring. boring is death. death is no fun. infinite loop. break;
I went to a few places after leaving my last company. What's the first thing you get after entering the building? Right! A form to fill! In some of the places, there is a cute line "desired pay: ______" in between the other lines of personal information. So you write something up (you can always leave it blank, but it will be the first question you'll be asked in those places, so save your breath), fill the rest of the form and returning it. Nice. So far, have I managed to hit 95% of your interviews experiences?
Next step. "Please sir(in Hebrew it sounds a lot WORSE, it's something like "this way man, hurry", but with a big smile), meet our HR girl(always a girl, and 99% of the time, she takes your mind out of the job)". You go in. Talk for a bit and than it arise: "Wow! X money! really?! maybe you slipped a 0 at the end ? no? oh... That is really a lot! are your sure? You do? oh....". I just hate it. I can't help to think:"Do you know what is a variable that you speak about money! I can be the next Don Box and you yabbing about money!?!" Yes, it's bullet number 1 in the "negotiations for dummies" book (I wonder if such a thing exists). So you explain and you argue and if you're convincing you continue. "Please sir ("faster you killer-budget" in Hebrew, and that smile again), lets meet our Team Leader\CTO". And what is the first thing that happens there? You know the answer ? Wow? Who told you? Oh.... you've been there haven't you?
"Hey [cute girl's name], Let me see the form he filled.... hmmm... I see.... "...
And of course, he is thinking inside "what?! that's is double than what I earn! and I'm the frickin' best in the industry!... Ok bastard, bring it on, you say you worth it ah? let's see..."
Kiss your interview goodbye. You can be Brad Abrams or Juval Lowy. It doesn't really matter. You are at war and sadly you can't win this one. You are either stupid to get what you want and arrogant to even request it or too arrogant for saying the right answers all the time.
One of the reason, among 1000 more reasons, that I've chosen Mercury as my new home was for that reason. We didn't talk about $$$ until the far end (after 2.5 technical interviews, 1 management interview and 1 HR interview). They were really interested in ME, not it the paycheck I request.
A very good comment will be "But what if we can't pay him that much? Isn't it a waste of time to go so far and at the end say to him that he requests more than we can offer". I'm with you guys. Every company has their budget. Limits should be set, no matter(?) how good this person is. But at least don't let the interviewer see anything related to money! It shouldn't bother him! And I've seen this pattern in so many places. What a shame. It happened to me in two places and I immediately "turned off" at the beginning. I knew that I'm not going to be a part of such a place and did my best to show the "better than you and still earn less" that tried to play it rough that I can raise to his challenge. After all, I want to have fun in interviews, no matter how bad it goes. My tip for you is: Let it be known, good places do exists, and good guys have a room there, just be patient and have the confidence in your abilities. Don't be afraid of bad interviews, it's good experience and it can be fun. Play your best game.
State of mind.
This is tricky, read the next paragraph and than think about it with your eyes closed.
Imagine that you are at work now, and doing the stuff you like so much. Think about the things you made that make you happy and proud, about the people you met that made you a better person and a better worker. Consider how in one hour you managed to write 10 hours work. Think about the happy customers you made. Smile. Now open your eyes.
What comes through your mind? What made this all possible? I don't know about you, but my feelings were:
1. The people. What a bunch of great people. I love them all. They enrich me and make my time better. This is my 2nd home.
2. The challenge. So many great things to think about during the day, so many challenges to figure out, so many small wins in a long but glorious battle. so many loses, but so many insights.
3. Pride. My code means something, I 100% believe in it. I'm proud of my code and I'm working hard to worth the respect from my friends at work.
this is just from the top of my mind, no re-write here. this is the set of mind you need to set for your interviewee in order to achieve "good interview" experience. You're questions must let him understand that he could be a part of a great bunch of people, that challenges will be there for him and so is help and friendship. You should let him know that HIS thoughts and HIS answers and questions are important in this interview. You should let him know that pride is there for reach. We all love a good word here and there. You should let him understand that this can be his new home.
Remember the feeling you had after you open your eyes. That should be the interviewee's feeling at the beginning of the interview and during it. I explicitly mentioned the word "beginning" as people are nervous at the beginning, so it's extremely important that you'll start slow and let the interviewee know that you want to get to know HIM, no matter how bad\good he\she* answers your questions.
Good .vs. Bad questions.
These are a few questions that only the "best" (my best) companies asked me and I feel that it's important to share them with you. Good questions are question with space. think about driving to your work at morning. You wake up and listen to the radio: "Road 5 is jammed between this and that". "Oh... So I would probably drive in road number 2 and cut to road number 4... It's longer(length) but faster". Roads give you space to decide. Usually. Good questions are the same. The (interviewee's)answer is irrelevant (you can always ask someone how to get to ThatIsTheOne st. if you nearby) as long as his mind is set for the right questions and answers. If he is not in the right path, help him out a bit(to an extent of course). For the interviewers among you, please, If there is one thing I would like you to take from this post is this: You are interviewing someone else, not yourself. That is why good questions allow the interviewee the space to let the interviewer konw what he thinks, may it be a complete joke. If it will be supplied with good reasons, than damn - I want this guy on my team. He is creative! I would not think about this option by myself.
Good personal questions I love to hear to start with:
"Tell me about an API of some class you wrote. What was the purpose? Is it(the class) good? how do you know? Would you change it now if you could, if so - why? Are you proud of that class? Tell me why."
"Do you read books\articles in the subject(any subject that you think is fit)? if so, tell me about a thing or to you picked up and how did it affect your work? tell me about something you found in one resource that you couldn't find in any other place. Why do you think it's only there? Do you write things yourself? Why? Do you enjoy it?"
"Do you love doing what you're doing? Tell me about it, why do you love it so much? do you take things "to bed"? do you love to think about work after work hours? do you think that this is a good thing?"
"Did you made a change in the last place you worked at? If so - tell me how. Are you proud of that change? Do you like to change places you work at? Did you get recognition about it? If so - did you enjoy it?"
"Why do you think you are good at what you're doing? Please give me examples of what makes you more special than the "next guy". What are you really good at? Do you think that it's possible for you to get better at it? Can you teach others? do you enjoy it?"
This should let you a good look at the inside of the interviewee, about his true nature, his true character. There is no fear here. No mistakes. Every answer is OK. This is simply how he\she is wired. I would always start with these questions as they will set the right mood. After talking about his personality and a little digging through his code, we can decide that the personality is not suited for the team and tell him goodbye or we can go a little deeper into the technical stuff.
Technical questions style I love to hear:
I love thinking questions (surprise surprise). Show a given algorithm and let the interviewee tell you what he believe that this code does. Talk about general syntax and basic patterns and see if he follows. Don't let him know if he is correct or not at the beginning, no fun in that.
Try to focus on algorithms instead of hardcore-"who cares?!" questions. Remember, it's all about space. If there is no place for multiple choices and multiple answers, you are doing it wrong. Always try to give hard questions in between, something nice that will show the interviewee that we are having fun, but we also mean business. Try to challenge and guide him for the solution. Always, always, let him get to the solution by himself, help him only with clues until he figure it out.
To recap, I am a big fan of Logic\Tree\Recursive solutions\Object Oriented\Design Patterns questions rather than "what this line of code will do: int i=10; i = i++*++i;". There are variety of questions out there, pick the ones you like the most and have a nice list of them so you can change the questions from time to time.
People make the company. Your interview should leave you with the best people and those (best)people should want to work for you after that interview. Invest time teaching your employees how to make interviews for others(if they need to have that skill). Hiring is the company's core, no less.
* I'm sorry if I wrote he instead of he\she somewhere in this post. We are all son of God(are we?).