House MD: Solving Complex IT Issues Using Differential

House MD: Solving Complex IT
Issues Using Differential Diagnosis

Steve Bennett

Steve@DaemonSolutions.com
@DaemonSteve

Saturday, 30 June 12

AGENDA
A Brief History Of Medical Diagnosis.
Why & How You Should Prove Yourself Wrong.
Differential Diagnosis.
Diagnostic Approaches.
Diagnostic Thresholds.
Do’s, Don’ts & Application.


Who’s This Guy?


Why...?


http://www.technologyreview.com/tr35/proﬁle.aspx?TRID=1108


http://flic.kr/p/npaoT


http://4.bp.blogspot.com/_lSXhEtQUdtA/S-EL5w7dt3I/AAAAAAAAANE/G0oc_cGPXAY/s320/USAirways+in+the+water.jpg


Medical Diagnosis


http://4.bp.blogspot.com/-cCTr1WWve1E/TfefWAn8zvI/AAAAAAAAAA0/aXO50-syXuE/s1600/Imhotep_Museum-hd-1.jpg

Imhotep - 2600BC

http://en.wikipedia.org/wiki/File:Edwin_Smith_Papyrus_v2.jpg


http://www.sculpturegallery.com/two/hippocrates3.jpg

Hippocrates - 460BC

http://www.sculpturegallery.com/two/hippocrates3.jpg

Galen - AD131

In Summary;
It’s Been Around A Long Time..


Hypothetico-Deductive Model


William Whewell


"No amount of experimentation can ever prove
me right; a single experiment can prove me
wrong."
Albert Einstein


Hypothetico-deductive model


Something unexplained happens.

http://www.ﬂickr.com/photos/dougcaldwell/4213877479

Hypothesize.


Plan a test that can falsify.
Predict the result.


Test.

http://www.ﬂickr.com/photos/kenilio/3351824931


Hypothesize.
Predict.
Test.


An Example.


I went shopping..


Failed Card
http://ﬂic.kr/p/9MShdE


Something unexplained happens.


Hypothesise.


I’ve Spent Too Much On SSD’s

My Wife Has Been Shopping

Hypothesise.

There Is A System Problem

I Didn’t Pay My Bill In Time


Plan a test.
Predict.


Test: I’ll call the credit card company.

Plan a test.
Predict.


Test: I’ll call the credit card company.

Plan a test.
Predict.

Prediction: I have sufﬁcient funds.

(If correct will falsify 3 hypothesis)


Test.


Test.

Result: I have sufﬁcient funds.


Hypothesise.

There Is A System Problem


Hypothetico-Deductive Model

Hypothesise.
Predict.
Test.


Or DDx


What is it?


It’s that thing that House does.


It's a framework for problem diagnosis.


It's best used alongside the
hypothetico-deductive model.


Process of elimination.


Assume most obvious.
Until proved otherwise.


"When you hear hoof beats, look for horses,
not zebras"


Probability is your friend.

http://www.ﬂickr.com/photos/nashnosh/5922580484


Personalised probability is your best buddy.

http://www.ﬂickr.com/photos/el5ajoola/3868649830


Here’s how it works.


Something happens.


Something bad happens.


Something bad and complicated happens.


Gather the facts...


Gather the facts...
Symptoms


Gather the facts...
Symptoms
Subject history
Previous test results
General observations


What else do we know?


http://www.ﬂickr.com/photos/dougcaldwell/4213877479

Hypothesise.


List Hypotheses.


Immediately discount.
Apply probability.


Prioritise hypothesis based on risk and
probability.


Plan tests.
Predict results.


Test.
Or Treat.


Feedback results.


Continue until diagnosis is conﬁrmed.

http://www.o-min.com/wp-content/uploads/mobius1-300x225.jpg



Gather the facts.
Hypothesise.
Apply Probability.
Prioritise.
Test or Treat.
Loop.


Diagnostic Approach


Possibilistic


Possibilistic
All Possibilities Are Equal

Test Everything


Probablistic


Probablistic
Selection Based On Probability

Prioritise The Most Likely


Prognostic


Prognostic
Selection Based On Most Serious

Prioritise The Most Serious


Pragmatic


Pragmatic
Selection Based On Responsiveness To Treatment

Prioritise The Most Easily Treated


When do I use each approach..


Do something and do it fast...

Pragmatic.


If it really is that, we are in a world of hurt.

Prognostic.


Default = Probabilistic.


I want more probability...


Pre & Post Test Probability.

Current Probability: 30%

If the result is X;
There is 60% chance of hypothesis being correct.

If the result is Y;
There is 0% chance of hypothesis being correct.

This is easier in medicine.


! Differential Diagnosis...
! Diagnostic Approach...


Diagnostic Thresholds


Deﬁne the point at which something is worth
testing.


Probability of Diagnosis
0% 100%
Test Treatment
Threshold High Priority Tests Threshold

Not Worth Worth
Testing Worth Testing Treating


Mnemonics.


Doctors Love Mnemonics.


Mnemonic for DDx.


Vascular
Idiopathic/Intoxication
Neoplastic
Degenerative/Deﬁciency
Inﬂammatory
Congenital
Autoimmune/Allergic
Traumatic
Endocrine


Mnemonic for Acute Pancreatitis.


GET SMASH’D
Gallstones
Ethanol
Trauma
Steroids
Mumps
Autoimmune
Scorpion bites
Hyperlipidemia
Drugs(azathioprine, diuretics)


Mnemonic for the web...


Users Operating system

Web server
Network

Cache/Code Application engine

Hardware
Services (Third Party) Database/Datastore

Cache/Code
Application engine
Services (Third Party)
Hardware
Web server
Operating system
Users
Network
Database/Datastore

CA$HWOUND

These are used to follow a path through trees.


C
A
$
H
W
O
U
N
D

How can this all help me?


It makes you more thorough.


It can help you ﬁx things faster.


By working as a team.


By working more efﬁciently.


Reduces Thematic Vagabonding.

http://www.ﬂickr.com/photos/neloqua/166353267


Reduces Lone Wolf Heroism.

http://www.ﬂickr.com/photos/tambako/3559257456


Reduces Encystation

http://www.ﬂickr.com/photos/tambako/3559257456

http://www.ﬂickr.com/photos/emmacoulston/4442688125


This is what it looks like.


I’ve run out of diagnosis.


You suck.
:-)


Then you’ve missed something.


Question your results, symptoms and
observations.


Re-test if in doubt.


Call in a fresh pair of eyes.


Do’s and Don’ts


Assemble a team.


Get the right experts in the room.


Experts and generalists.


The diagnostic lead.


Diagnostic Lead, controls the pen.

http://www.ﬂickr.com/photos/scttw/1819085915


Take it in turns to lead.

Culture.


http://www.ﬂickr.com/photos/41427839@N07/5973163369/

Openness is key.


Encourage people to challenge.


And be challenged.


http://www.neale-wade.net/blog/wp-content/uploads/2008/08/100_1241.jpg

Collaborate.

Do not immediately dismiss ideas...

http://www.ﬂickr.com/photos/albaﬂickr/4416770182/lightbox/


that were not yours...



that were not yours...
or your team’s...



http://www.ﬂickr.com/photos/straubin/4541508733/

There is a time to debate and a time to act.

http://www.ﬂickr.com/photos/54182266@N02/5017666438


Get better at making group decisions.


Build a culture that encourages creative
suggestions.


Practice makes perfect.


When do I use this..?


Complex Problems.


Active Problems.


Post Mortem


Conclusion


Try and prove yourself wrong.


DDx is a framework that YOU can use to
resolve & manage your complex problems.

Be aware of the Diagnostic Approach that you
are using and why.


Create a
Mnemonic for
your system.

It acts as a
checklist.


Watch House.


Further Reading;
The Process of Diagnosis (AMA) -
http://medicine.ucsf.edu/education/resed/articles/jama6_the_process.pdf

Jessie Robbins - Creating Resiliency Through Destruction-
http://www.slideshare.net/jesserobbins/ameday-creating-resiliency-through-destruction

All of John Allspaw’s presentations-
http://www.slideshare.net/jallspaw

House MD
http://www.fox.com/house/


Thank You.
:-)


House MD: Solving Complex IT Issues Using Differential

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House MD: Solving Complex IT Issues Using Differential