Introduction and technical overview The need for a model How can we demonstrate program feasibility A timestepping model of program delivery is needed to demonstrate program feasibility t o test program coverage and quantify impact ID: 501460
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Slide1
Word-of-Mouth Modelling
Introduction and technical overviewSlide2
The need for a model
How can we demonstrate program feasibility?
A time-stepping model of program delivery is needed:
to demonstrate program feasibility
t
o test program coverage and quantify impact
to answer difficult questions on how to deliver the program (e.g. how many educators per community, what size of community should we target)
to maximize operational cost-effectivenessSlide3
Modelling
Key question: how many people can we reach with this program in a given number of years?
Given:
certain sociological and cultural factors governing the dissemination of such introduced knowledge
t
he size of the target community
t
he number of educators that we train to actively spread knowledge in the communitySlide4
Models for related phenomena
Models are commonly used to understand the spread of diseases
A modification of the model was made to simulate the spread of rumours. (Daley-Kendall model, 1964)
Modelling the spread of disease
University of Colorado Mathematical Biology GroupSlide5
Daley-Kendall Model
State
Has not heard of rumour
State
Actively spreading rumour
State
Knows rumour, but no longer spreads it
Attempted to spread rumour to a person who already knows it
rumour no longer “news”
Told rumour by someone in state
Slide6
Proposing a new model
Spreading advice has very different dynamics to both of the above.
Rumours are spread as long as the rumour is considered “news”.
Advice on maternal care follow an opposite model.
Cultural and sociological factors as well as reservations on believing the advice is good and valuable may slow or stop the spread of advice.
In a smaller community, the advice is likely to gain widespread acceptance, fueling its own spread.Slide7
Our model
State
Has not heard of advice
State
Spreading advice, slowly and with strong reservations
State
Aggressively spreading advice
Attempted to spread advice to a person who already knows it
increases advice acceptance
Told rumour by community educator or someone else in state
Stochastic decay of advice value (advice loses credibility, forgotten, etc.)Slide8
Model completeness
The model is “complete” in that it models all the key factors causing word-of-mouth propagation.
An arbitrary number of
states can be added.
Parameters are to be adjusted.
Model approaches the real phenomena as
and parameters are corrected!
Model is reducible to Daley-Kendall (simply set
to 0% spread and remove
)
Slide9
Key parameters and assumptions
5 educators
gets around to
teaching about 48 women a month, through one means or another (pamphlets, attending births,
etc
)
An individual will only spread the idea for about
two
months unless the idea becomes
“accepted”
Based on the average births per female and the average female life expectancy, along with an estimate of how many individual females that a person will know on average, we calculate how likely individuals will engage in maternal health conversation.
The estimate is about once every two months, but increases dramatically if the idea becomes accepted.Slide10
Parameters
The parameters were set on a per-day basis. Simple math was used to extrapolate these variables to monthly figures which are more informative.
Per month, 48 individuals are converted from
to
. (1.6 per day)
Each individual in
has a 1.8% chance of spreading the advice in a given day. (0.55 people a month)
Each individual in
has a 7.3% chance of spreading the advice in a given day. (2.2 people a month)
Each day, a number of people in
decreases to
at 0.5% a day.
Each day, a number of people in
decreases to
at 3% a day.