A friend pointed me to How
to crack product metric questions in PM interviews. In essence, it
discusses how does a service provider respond to a change in a metric or
KPI (Key Performance Indicator).
A definition from the article:
Metric interview questions test if candidates can perform data analysis
and select key metrics that matter most to the success of a product.
Employers like Facebook and Google use these questions to evaluate
critical thinking and communication skills.
There are two types of metric questions - one builds on the other
| Metric definition questions |
Metric change questions |
- What are the metrics that provide clarity on the health of a
product or feature?
- What metrics matter??
|
- Do you know what to do when a key product metric (e.g.
traffic, revenue, engagement, etc.) is going up or down for no
apparent reason.
|
Solving the Metric definition question
The article recommends the use the GAME
method
| Goals |
- Make sure you understand how the functionality helps the
commercial goals of the company.
- 80/20 rule - make sure you're measuring the 80% - the stuff
that matters!
|
| Actions |
- What are key activities that indicate the functionality is
achieving those goals?
- This requires good understanding of the product functionality.
- Make sure that DevOps doesn't define and implement these
unsupervised!!
|
| Metrics |
- Where in the value chain is a good place to position a
measurement?
- Yes or No evaluation is a starting point, but is there another
metric that is a precursor to the switch toggling from one
condition to another?
- In web performance management ie website availability and
uptime, then "What goes slow, goes down." (see the Webmetrics
case study)
|
| Evaluation |
- What is normal, good or bad about a metric reading?
- And are the trade-offs and limitations in having this figure?
- For example, seeing a drop in shopping basket conversions over
a 24 hour period might be useless without understanding that
there was 60 minute outage from your payment provider.
|
Solving the Metric Change question
The article provides its own methodology.
| Define the metric change |
Make sure you fully understand the metric that is being presented
to you:
- What is it and what is it not?
- You may have to get into the weeds about how the metric is
measured. See Actions above
- For example is 'Page Views' the total number of views or page
views by unique users? What happens if the same user logs in and
views the page on two devices or two different sessions, how is
that logged?
|
| Explore possible root-causes of the
change |
Use the MECE
framework
- Mutually Exclusive and Collectively Exhaustive = Identify
cause(s) that is independent of all others OR understand what
the cause is definitely NOT (*).
- For a metric incident, the root-cause of the problem has to be
internal OR external, as there is no other option.
- If you think there is an internal AND an external cause,
then you need to do more research. Did one external condition
cascade to an internal condition?
- Unfortunately, these can be super hard to run
down!
|
| Conclude |
Make sure there aren't any horrible assumptions that you haven't
validated / eliminated. |
* For info on MECE:
Escalation and Communication
The article hardly touches on the critical, critical
point of issue escalation and communication.
After you have done your initial assessment, you need to answer
the question: Do I ring the alarm bell and to whom?
Judgement call: Let's assume that (a) the metric isn't a false positive
and you've validated to some significant extent (b) the metric matters.
So, how high do you escalate the issue?
Factors to consider:
- How many other business functions are impacted by the incident?
- Is that metric important to them?
- Can they do something about it, either to resolve it (eg some
root-cause analysis) or to reconfigure their business function to
accommodate the impact of the incident?
I recommend using this yard stick:
| Level of concern |
Action |
| Not a concern or quickly solved and
implemented |
- If you are sure that impact is minimal and contained, then I
recommend concentrating on solving the issue.
- You can report that the problem was resolved with minimal
impact.
- Warning: if you get stuck in the resolution, then you quickly
have to over-escalate the issue eg to 'Very concerning'
|
| Somewhat concerning, but impact is
contained |
- Keep researching until either you hit a brick wall or an
unreasonable amount of time has elapsed
|
| Very concerning |
- More business functions are required to investigate and you
need to escalate it to a suitably high level to get resources
devoted to it.
- When communicating, be clear to separate known symptoms vs
known conclusions to date vs guestimates as to possible causes,
articulate mitigating factors and (partial) resolutions that
have been applied to date.
|
| Ridiculously high |
- This is a hard one to call. You most probably know that
something basic has gone wrong and that others have spotted it
and are working on a solution (and may have even resolved it).
- However, that is a dangerous assumption. It's best to escalate
it - even if it is likely to be a false positive.
|
The importance of communicating - and re-communicating
As soon as you communicate outside of your team, make sure that someone
is knowingly and consistently appointed as Incident Manager (ie it could
be you!). Note that if the problem rattles on, then you may need to
appoint a Communications Manager in front of the Incident Manager to
protect the Incident Manager from simply responding to communication
enquiries rather than actually working on the resolution.
It's best also to alert other business functions how you will update them
on progress and frequency of updates (even if there is no progress).
Use of incident support tools
There is a great danger in over-engineering the use of incident support
tools. Over-engineering = it is too clumsy or laborious at the point of
the crisis. If others aren't familiar with the tools, then they will still
ask for email / telephone / instant messenger updates anyway!
Next step: Deep Dive into Root-Cause Analysis
Once you have done your initial assessment and then communicated your
initial findings to relevant business function, it's time to dive deep
to separate symptoms from root-cause. You may need access to multiple test
and near-production systems(*) to validate theories.So do make sure these
are functional before the crisis hits.
Do ask around your team (DevOps, Release Management, Testing,
Engineering) for their input into symptoms and route cause. In many
circumstances, something similar has been seen before.
Cycle back with colleagues and partners based on status and resolution -
instant messenger is fab here!
(*) Near-production = an environment that mostly closely replicates your
live or production environment
Multiple resolutions
There may be several resolutions available: there's a matrix of time
horizon vs cost-benefit.
Multiple resolutions might be appropriate - and that's absolutely appropriate to pursue several simultaneously. eg roll-back recent
enhancement; test proposed partial fix; kick back to engineering for a
rework with new testing scenarios etc.