House MD: Solving Complex IT Issues Using Differential

House MD: Solving Complex IT Issues Using Differential Diagnosis

Steve Bennett

[email protected]@DaemonSteve

Saturday, 30 June 12

mailto:[email protected]

mailto:[email protected]

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 - 2600BCSaturday, 30 June 12



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




Hippocrates - 460BC

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




Galen - AD131http://www.sculpturegallery.com/two/hippocrates3.jpg


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.


Hypothesize.

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




Plan a test that can falsify.Predict the result.


Test.

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




Hypothesize.Plan a test that can falsify.

Predict.Test.


An Example.


I went shopping..




Failed Card

http://flic.kr/p/9MShdE





Hypothetico-deductive model


Something unexplained happens.


Hypothesise.


Hypothesise.

There Is A System Problem

My Wife Has Been Shopping

I Didn’t Pay My Bill In Time

I’ve Spent Too Much On SSD’s


Plan a test.Predict.



Test: I’ll call the credit card company.



Test: I’ll call the credit card company.

Prediction: I have sufficient funds.

(If correct will falsify 3 hypothesis)


Test.


Test.

Result: I have sufficient funds.


Hypothesise.


My Wife Has Been Shopping

I Didn’t Pay My Bill In Time

I’ve Spent Too Much On SSD’s


Hypothesise.



Hypothetico-Deductive Model

Hypothesise.Plan a test that can falsify.

Predict.Test.


Differential Diagnosis.


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...

Subject history

Previous test results

Symptoms

General observations


What else do we know?


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.

Differential Diagnosis.


Diagnostic Approach


Possibilistic


Possibilistic

All Possibilities Are Equal

Test Everything


Possibilistic

All Possibilities Are Equal

Test Everything


Probablistic


Probablistic

Selection Based On Probability

Prioritise The Most Likely


Probablistic

Selection Based On Probability

Prioritise The Most Likely


Prognostic


Prognostic

Selection Based On Most Serious

Prioritise The Most Serious


Prognostic

Selection Based On Most Serious

Prioritise The Most Serious


Pragmatic


Pragmatic

Selection Based On Responsiveness To Treatment

Prioritise The Most Easily Treated


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.

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.

Current Probability: 30%


This is easier in medicine.


Differential Diagnosis...Diagnostic Approach...

!

!


Diagnostic Thresholds


Define the point at which something is worth testing.


0% 100%Test

ThresholdTreatmentThreshold

Probability of Diagnosis

Worth TestingNot Worth

TestingWorth

Treating

High Priority Tests


Mnemonics.


Doctors Love Mnemonics.


Mnemonic for DDx.


Vascular

Inflammatory

NeoplasticDegenerative/Deficiency

Idiopathic/Intoxication

CongenitalAutoimmune/Allergic

EndocrineTraumatic


Mnemonic for Acute Pancreatitis.


Gallstones

Mumps

TraumaSteroids

Ethanol

AutoimmuneScorpion bites

Drugs(azathioprine, diuretics)Hyperlipidemia

GET SMASH’D


Mnemonic for the web...


Cache/Code Application engine

Services (Third Party)Hardware

Web server

Operating systemUsers

Network

Database/DatastoreSaturday, 30 June 12

Cache/CodeApplication engineServices (Third Party)HardwareWeb serverOperating systemUsersNetworkDatabase/Datastore

CA$HWOUNDSaturday, 30 June 12

These are used to follow a path through trees.


CA$HWOUND


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/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.Saturday, 30 June 12

Culture.


Openness is key.

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




Encourage people to challenge.


And be challenged.


Collaborate.

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




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...




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

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

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 MDhttp://www.fox.com/house/


















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

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

Thank You.:-)

��Saturday, 30 June 12

Technology

House MD: Solving Complex IT Issues Using Differential