Some background
on the thesis...

The problem

Each mass gathering requires a
Risk assessment

Generate patient scenarios
Where each scenario is
an attendee requiring first aid

Simple (roulette wheel) scenario generation

Better scenario generation...

Instead of:

Pr( Asthma )

Condition on the characteristics of the event:

Pr( Asthma | Seated, Indoors, Alcohol, etc... )

And ignore those things which don't matter:

Pr( Asthma | Indoors )

As it happens...
Bayesian Networks
are pretty good for this

Constructing a Bayesian Network

Using data and algorithms:

Analyse the data sets for relationships.

Using experts and their knowledge:

Elicit knowledge from experts about relationships.

This part of the project presents
A technique for expert elicitation
of Bayesian Networks

This technique is to existing techniques
Surveys are to interviews

The analogy (in sweeping generalisations)

  • Surveys are rigid
  • Surveys require more questions
  • Interviews are flexible
  • Interviews require less questions

  • Surveys require less coordination
  • Surveys require less commitment from the participant
  • Surveys don't require transcribing
    (if done online)
  • Interviews require more coordination
  • Interviews require more commitment from the participant
  • Interviews require transcribing

  • Surveys reach
    more people
  • Interviews reach
    less people

How can the
Survey analogy be used to
elicit Bayesian Networks?

Consider this way of conceptualising a Bayesian Network:
A (sparse) matrix of relationships

Should we ask the expert to fill in this matrix?

We can
Constrain the possibilities

Variables cannot influence themselves...

...and injuries cannot influence event characteristics...

...and we assume each patient only has one injury...

...and we usually know the event characteristics...

All of a sudden it is not so sparse

Specifying the presence of relationships via the matrix
doesn't allow experts to:

So we replace the matrix with
More understandable questions


A word I just made up for this talk...

When is a Delphi round complete?

All participants have finished.

or when

A certain time has elapsed.

After each round,
Remove unused variables
Provide feedback,
then do it again

Removing variables which nobody selected

Provide feedback by
Identifying the odd ones out

Provide them with results from other participants.

Ask them to clarify or correct their stance.

When is the whole thing complete?

The parents of each variable cease to change.

or when

A certain number of rounds has completed.

The study participants

Enlisting people with
Experience in
Mass gathering medical care

Current status of PhD

is approaching completion.

is pending approval.

will start after ethics.

is up to 35,000 words.

Two more publications
are planned.

Thanks for listening
Any questions?