Architecture of Tech Interviews

Gayle L. McDowell | Founder / CEO, CareerCup

gayle in/gaylemcdgayle

The Architecture of InterviewsConsistency + Efficiency + High Bar + Happiness

June 7, 2016 | Talent42

&candidates are

frustrated confused

gayle in/gaylemcdgayle 3Gayle Laakmann McDowell

TheyDon’t

Know…

How many interviews Who will be interviewing If they’ll code? How? What they need to know How decision gets made WHY?

Lots of myths (and misinformation)!

&&

companies need

consistency efficiency

high bar happiness

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Consistency & Efficiency

Consistency Outcome Process Questions

Efficiency Speedy process Able to expedite Minimal overhead Minimal false

negatives


High Bar & Happiness

High Bar Minimize false

positives Good, adaptable

people

Happiness Enjoyable

experience Makes company

look good Transparency

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The Process

Resume Selection

Intro Call w/ Recruiter

Email that outlines process

Code Assessment

Phone Interview

~4 onsite interviews

Discussion & Decision

“Sell” Call / Dinner

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StuffI’ll

Discuss

Bar Raisers vs. Hiring Committees

Offline Work Homework vs code assessment tools

Question Style Knowledge, algorithms, pair

programming Coding Platform

Real code vs. pseudocode Whiteboard vs. computer

Bar Raisers or Hiring CommitteesSo different, yet so similar01


Bar Raisers and HC

Offer transparency Offer consistency Keep bar high Facilitate change Can override manager

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Hiring CommitteeCons Overhead Delays Un-empowering Can feel “black

box” Need good

feedback

Pros Cross-company

consistency Keeps bar high Easier to improve

process


Who’s it good for?

Companies that: See 5 or more dev candidates per week Want to improve process Hire for company, not team Are not very knowledge focused

Easier to implement early!


Hiring Committee: Best Practices

Meet at least 2x per week Multiple HCs:

Beware of bar creep / inconsistencies Let interviewers observe HC Train interviewers to write feedback

Quality of decisions rests on feedback


Bar RaisersCons Need consistency

across company Need to scale team

Pros Many of HC benefits:

Consistency High bar Transparency

But easier to implement

No bottleneck


Bar Raisers: Best Practices Select people who are inherently good

Experienced at interviewing Nice, empathetic Smart & can challenge candidate

Train them thoroughly Empower them Assign outside of team Watch out for scale/exhaustion!

Offline AssessmentsHomework, code assessment tools, etc02


Offline AssessmentsHomework Projects Code Assessment Tools


Homework Projects

Big Very Practical Some love

this Less cheating

Except: algos

Too immediate Needs eng time Disproportionate

workload Scales poorly for candidate


Homework: Best Practices

Show candidate interest first

< 4 hours If >4, onsite

project review

Architecture, not algorithms

Define review criteria

Avoid confusion with company work


Homework: Who It’s Good For

Language focused Low priority on algorithms / thought process

Experienced candidates (maybe)


Code Assessment Tools Fast, cheap eval

More candidates Non-traditional

Sets expectations for onsite

Consistent data point

Cheating May turn off

senior candidates


Implementation Options

Everyone Just your “maybe” candidates Fast-Track


Who It’s Good For

Small, mid-sized, and big companies Value algorithms / problem solving Lots of candidates Want to look at non-traditional

candidates


Code Assessment: Best Practices Show candidate

interest first Beware of

cheating (But no biggie!)

Clear expectations

Pick GREAT questions Similar to real

interviews Unique

questions 1 – 2 hour test

Question StylePair programming, algorithms, knowledge03


What To Ask

Knowledge Algorithms Design/Architecture Pair programming


Knowledge Questions

Good when you can’t train skill easily

Best practice: In-depth, if at all Keep it a discussion


Algorithm Questions

Smart matters. Good for everyone Best practices:

Clear expectations with interviewers & candidates

Ask medium-to-hard & unusual questions


Design/Architecture

Great for experienced candidates Shows communication skills Best practice:

Prep candidates. Big unknown!


Pair Programming Many candidates

enjoy it Feels fair & real

world Assesses code

style / structure Shows

interpersonal interaction

Less understood Not great for algos Interviewer really

matters Biased by tools


Pair Programming: Best Practices Prep/warn candidates Need GREAT interviewer Give choice of problems Okay/good to pick unreasonably big problems Guide candidates

(Okay to ask questions, not know tools, etc.)

Coding PlatformWhiteboard vs. Computers04


Why We Make Them Code

Can they put “thoughts” into “actions”?

Do they show good structure and style?

Do they think about the impact of decisions?

Why not pseudocode?

A Game with Secret Rules

… and this is for a simple problem


Don’t Allow Pseudocode

Unpredictable playing field Details matter If “real code” is too hard for them…


How to Code

Big Practical Stuff Use computer Pair

Programming

Small Stuff Algorithm-

focused Computer or

whiteboard


But how to code?whiteboard computer


A Case for Computers Realistic. Allows tools. Candidates feel more comfortable

(Especially experienced & diversity candidates) Faster to write (often)

More code


The Downside of Computers

Often write stupid stuff Desperate attempt for compilation Communication shuts down Biased by tools/laptop “Transition” between algorithm &

code

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Gayle Laakmann McDowell

Computer

BestPractices

Let candidate bring laptop

Instruct: not every detail

Encourage communication and thinking

Recognize the bias!


A Case for Whiteboards

Encourages thinking & communication More language agnostic Consistent across candidates

Better laptop/tools doesn’t matter It’s “standard”


The Downside of Whiteboards

Slow to write Artificial environment Can be intimidating

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Gayle Laakmann McDowell

Whiteboard

BestPractices

Encourage shorthand

Be upbeat & encouraging

Reasonable expectations


Recommendations

If skill-focused: then ComputerIf algos-focused: then WhiteboardIf a little of each: then Either/or

Both can work! … with proper training

Why not let candidate choose?

Last Remarks05


Things to Consider Bar Raisers or Hiring Committees Code assessment tools Pair programming (for practical stuff) Whiteboard (or pick-your-poison) for algorithms

stuff

there is noperfect system

THANK [email protected]

gayle in/gaylemcdgayle

Recruiting & HR

Architecture of Tech Interviews