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Creating the (Im)perfect Developer Interview


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How to hire software engineers. An overview of the different interview processes and questions, and where they fail.

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Creating the (Im)perfect Developer Interview

  1. 1. GayleL. McDowell | Founder/ CEO, CareerCup gayle in/gaylemcdgayle Creating the (Im)Perfect Dev Interview Process It’sall broken.Here’showto make it a littleless. Oct 14, 2015
  2. 2. gayle in/gaylemcdgayleGayle Laakmann McDowell 2 Hi! I’m Gayle LaakmannMcDowell Author Interview Coach Interview Consulting <dev> </dev> (CS) (MBA)
  3. 3. Gayle Laakmann McDowell 3gayle in/gaylemcdgayle Yes! Slidesare online!  Click“Events” Find Event
  4. 4. How People Hire Current strategies 01 Email: Subject: #interviewtraining
  5. 5. gayle in/gaylemcdgayle 5Gayle Laakmann McDowell How We Hire Problem-solving questions Onsite “real-world” tests Homework projects Take-Home Tests Prior experience References
  6. 6. Gayle Laakmann McDowell 6gayle in/gaylemcdgayle It’s all broken There’s no “perfect” interview. Always false negatives. Always false positives.
  7. 7. Gayle Laakmann McDowell 7gayle in/gaylemcdgayle Problem Solving Intelligence matters (a lot) Lots of communication Ability to push through hard problems Intimidating Prep helps Other ways to be “great” Can turn off sr. candidates Lots of bad questions
  8. 8. Gayle Laakmann McDowell 8gayle in/gaylemcdgayle Onsite Real-World Tests See real-world skills Identifiescurrent skill set, notpotential Lack of communication
  9. 9. Gayle Laakmann McDowell 9gayle in/gaylemcdgayle Homework Sees real-world skills. Cheap & easy Identifiescurrent skill set, notpotential Candidatescan feel exploited
  10. 10. Gayle Laakmann McDowell 10gayle in/gaylemcdgayle Prior Experience It matters Lots of communication Some can “talk a good game”  Somecan’t…
  11. 11. Gayle Laakmann McDowell 11gayle in/gaylemcdgayle References Prior experience is good Hand-picked Differentcompanies have differentneeds Not always 100% honest
  12. 12. gayle in/gaylemcdgayle 12 z Gayle Laakmann McDowell Not To Mention… NONE evaluate workethic or ability to focus (whichisn’tnecessarilyconstant anyway)
  13. 13. gayle in/gaylemcdgayle 13 z Gayle Laakmann McDowell What To Do? Find what’s right for you Identify theflaws Make it as un-brokenas possible Mix n’ match
  14. 14. Core Beliefs Philosophies around hiring 02 Email: Subject: #interviewtraining
  15. 15. Gayle Laakmann McDowell 15gayle in/gaylemcdgayle #1: Interviews don’tneed to mirror the real world
  16. 16. Gayle Laakmann McDowell 16gayle in/gaylemcdgayle #2: Goodcandidateexperiences matter
  17. 17. Gayle Laakmann McDowell 17gayle in/gaylemcdgayle #3: You’llnever have a perfect process
  18. 18. Gayle Laakmann McDowell 18gayle in/gaylemcdgayle #4: You need to THINK aboutyour process
  19. 19. The Process The Good, The Bad, The Ugly 03 Email: Subject: #interviewtraining
  20. 20. gayle in/gaylemcdgayleGayle Laakmann McDowell 20 A typical good process Resume Selection Intro Call w/ Recruiter Email that outlines process Code AssessmentPhone Interview ~4 onsite interviews Discussion & Decision “Sell” Lunch / Dinner
  21. 21. Gayle Laakmann McDowell 21gayle in/gaylemcdgayle Mistake#1: Expectations Mistake: Candidates don’t know what to expect  Howmany interviews? Will I be coding? What sorts of questions?  Leads to false negatives & bad reputations Fix: You should have a standard “what to expect” email.
  22. 22. Gayle Laakmann McDowell 22gayle in/gaylemcdgayle Mistake#2: Wasted Phone Interviews Mistake: Phoneinterview are often:  Tooeasy  Totallydifferentfromonsite Fix: Should match onsite interviews in difficulty &style
  23. 23. Gayle Laakmann McDowell 23gayle in/gaylemcdgayle Mistake#3: Lack of Structure Mistake: Interviews are often a “free for all”  Interviewersask whatever theywanttoask  Leadstorandomnessinprocess& unpreparedcandidates Fix:  Assign“focuses”upfront.  Traininterviews.
  24. 24. Gayle Laakmann McDowell 24gayle in/gaylemcdgayle Mistake#4: Not Knowing Your Numbers Mistake: You don’t know your metrics  Howwillyouknowtheissues? Fix: Knowand track:  Passrate ateachstage  Timetoget througheachstageofprocess  Average scorebyinterviewer  Correlationinphonevs.onsitescores  Typicalonsitevisits
  25. 25. The Interview What do you ask and why? 04 Email: Subject: #interviewtraining
  26. 26. gayle in/gaylemcdgayleGayle Laakmann McDowell 26 Goals Great employees, not great interviewees Good in 6 months,not 6 days Reduce falsenegatives Keepcandidates happy
  27. 27. gayle in/gaylemcdgayle 27Gayle Laakmann McDowell What Do You Need? Soft Skills / CultureFit Prior Experience Knowledge Open-EndedDesign ProblemSolving
  28. 28. Soft Skills / Culture Fit Yeah, you probably need it Email: Subject: #interviewtraining
  29. 29. gayle in/gaylemcdgayle 29 z Gayle Laakmann McDowell What Is It? Communicationskills Teamwork/Leadership CultureFit
  30. 30. Gayle Laakmann McDowell 30gayle in/gaylemcdgayle Where it goes wrong… Not gettingwhat you thinkyou’re getting  “Areyoumore detailorientedor bigpicture?” Cheesy questions  Get cannedresponse Your culture: notwhat you thinkit is
  31. 31. Gayle Laakmann McDowell 31gayle in/gaylemcdgayle Ask Yourself Whatisyour culture exactly? Can you identifythose things?How? Do you need to explicitlyidentify these? … Or is it just “no jerks”?
  32. 32. Gayle Laakmann McDowell 32gayle in/gaylemcdgayle Best Practices Define your culture /needs Identify whatyou need to assess  (orifyouneedtoassessit) Avoid cheesy questions Use experience, not hypotheticals
  33. 33. Prior Experience What have they done before? Email: Subject: #interviewtraining
  34. 34. gayle in/gaylemcdgayleGayle Laakmann McDowell 34 Why? Isthisapersonyouwanttoworkwith? Technical expertise  Hasmadegood,interestingtechnicaldecisions Culturefit/personality  Notarrogant,curious,initiative,etc. Communication  Can theyarticulateimpact?
  35. 35. Gayle Laakmann McDowell 35gayle in/gaylemcdgayle Where it goes wrong… Interviewers take answers as-is  Candidatesunderplayaccomplishments Overly specific questions
  36. 36. gayle in/gaylemcdgayleGayle Laakmann McDowell 36 Best Practices Probe deeper Be nice and friendly  (Evenifyoufeeldifferently) Stick to more technicaldiscussions ChallengeYOUR assumptions Inevery interview
  37. 37. gayle in/gaylemcdgayleGayle Laakmann McDowell 37 Evaluation A factor in ALL interviews Err towards listing minor concerns  Evenifit’sjusta “feeling” Challengeyour assumptions
  38. 38. gayle in/gaylemcdgayleGayle Laakmann McDowell 38 Best Practices Overly specific questions “Cheesy” canned questions Accepting answer as-is  Probedeeper Many people give TOO MUCH credit to team
  39. 39. gayle in/gaylemcdgayleGayle Laakmann McDowell 39 Examples Dive into a technicalproject  Walk throughdesignonwhiteboard  Discusstradeoffs,keydecisions,etc  Extensionstoproject(scaling,etc)  Focusonpersonalimpact
  40. 40. Technical Knowledge But do they know stuff? Email: Subject: #interviewtraining
  41. 41. Gayle Laakmann McDowell 41gayle in/gaylemcdgayle TechnicalKnowledge Can be a reflectionof depth Hires people who can makeimmediate impact
  42. 42. Gayle Laakmann McDowell 42gayle in/gaylemcdgayle Where it goes wrong… Too surface level Not a “reflection”of anything Lookingfor too many things  Shrinkscandidatepool  Disproportionateimpactonwomen
  43. 43. gayle in/gaylemcdgayle 43 z Gayle Laakmann McDowell Knowledge Should Be .... Hardto Acquire --or-- A redflag tolack
  44. 44. Gayle Laakmann McDowell 44gayle in/gaylemcdgayle Ask Yourself Do you really need that? Am I beingrealistic? How long wouldit take to learn? Do you havetheresources to train?
  45. 45. gayle in/gaylemcdgayleGayle Laakmann McDowell 45 Best Practices Hard to acquire ORa red flag Relevant to job Discussions > fact grilling  RuleofThumb:qualitative,notquantitative,evaluation  “Howdoes___ work?”  “Describewhenyouwoulduse__ vs__.”
  46. 46. Design Big, meaty problems Email: Subject: #interviewtraining
  47. 47. gayle in/gaylemcdgayleGayle Laakmann McDowell 47 Why? Tests:  Abilitytotackleopen-endedproblems  Communication/teamworkskills  Adifferentsideofproblem-solving Respects experience of senior candidates 47
  48. 48. gayle in/gaylemcdgayleGayle Laakmann McDowell 48 Best Practices Ask open-ended problems Encourage follow up questions Have candidate walk through Let candidatedrive 48
  49. 49. gayle in/gaylemcdgayleGayle Laakmann McDowell 49 Evaluation Ability to make tradeoffs Ability to identify issues Separate knowledge from attributes Response to feedback 49
  50. 50. gayle in/gaylemcdgayleGayle Laakmann McDowell 50 Bad Practices Unreasonable knowledgeexpectations Some candidates don’t know how it works  Can’taskquestions  More ofa factualanswer  Don’tdrivetheprocess 50
  51. 51. gayle in/gaylemcdgayleGayle Laakmann McDowell 51 Examples DesignAPI for… System for Amazon book rank System for TinyURL OOD for a music library 51
  52. 52. Problem Solving The smarts Email: Subject: #interviewtraining
  53. 53. gayle in/gaylemcdgayleGayle Laakmann McDowell 53 Why? Smart people do good work Hires adaptable people Very effectiveifdonewell 53
  54. 54. Gayle Laakmann McDowell 54gayle in/gaylemcdgayle Where it goes wrong… Bad questions  Tooeasy  Toocommon  Toomuchofa “trick” Bad process/coaching Bad evaluation techniques
  55. 55. Gayle Laakmann McDowell 55gayle in/gaylemcdgayle What makes a good question? Medium orhard Reasonable knowledge expectations Not common No single“a ha” moment
  56. 56. Gayle Laakmann McDowell 56gayle in/gaylemcdgayle How doyou ask them effectively? Coach candidates in helpfulways  “Whataboutanexample?” Give hints Remindthem of details Be positive and reassuring
  57. 57. Gayle Laakmann McDowell 57gayle in/gaylemcdgayle How doyou evaluatethem? Not about right vs. wrong Look for great solutions Take into account hintsand difficulty
  58. 58. Coding What you need and what you don’t Email: Subject: #interviewtraining
  59. 59. gayle in/gaylemcdgayleGayle Laakmann McDowell 59 Why? Code quality matters Not everyone can translatealgorithm into code
  60. 60. gayle in/gaylemcdgayleGayle Laakmann McDowell 60 Evaluation Look at structure and style  Butdifferentiatewhat’strainable Not about complete vs. incomplete Let the candidate test
  61. 61. gayle in/gaylemcdgayleGayle Laakmann McDowell 61 Bad Practices Requiring every detail Tedious questions Taking over the testing Lettingthe candidate code too early
  62. 62. gayle in/gaylemcdgayleGayle Laakmann McDowell 62 Goal: “Seeminglycompilable” code. Don’t waste time  DoyoureallyneedthatNodeclass?  Encourageabbreviations,skippinguninterestingparts,etc. Let the candidate test (first) Best Practices
  63. 63. Where do you go from here? Rolling out a great process 04 Email: Subject: #interviewtraining
  64. 64. Gayle Laakmann McDowell 64gayle in/gaylemcdgayle Define What YouValue Do you have a definedculture? Do you need specific, deep knowledge? Whichspecificexperiences matter? Do you solve hard-ish problems?
  65. 65. Gayle Laakmann McDowell 65gayle in/gaylemcdgayle TrainYour Interviewers Need dev-specific interview training  Teachwhyyouasksomequestions • … and why you shouldn’t teach others  Teachthemtocreate goodexperiences  Teachthemhowtoevaluate Shadow & evaluate interviewers Structure your interviews
  66. 66. Gayle Laakmann McDowell 66gayle in/gaylemcdgayle Keep Your CandidatesHappy Prepare your candidates  Theyshouldknowwhattoexpect Select friendly, effectiveinterviewers Move quickly Keepin touch!
  67. 67. gayle in/gaylemcdgayle 67Gayle Laakmann McDowell No process is perfect Find theleast-bad option Be aware of its weaknesses Fix as you go THINK!
  68. 68. THANK YOU gayle in/gaylemcdgayle Email: Subject: #interviewtraining