A cohort model issue

A place for Ventity software questions & answers
Senior Member
Posts: 51
Joined: Thu Nov 18, 2010 9:18 am

A cohort model issue

Postby moudi » Fri May 12, 2017 6:14 am


I would like to implement the following: At the onset of a coronary event a new entity is created (CHD Cohort). This cohort should receive the new cases with CHD (incidence rate CHD) as the initial value. My idea is that these cohorts are created continuously, but are nonzero only if they are populated with this incidence rate CHD. Deaths depend a) on age and a mortality rate depending on age and b) on a Standardized Mortality Ratio, depending on the time since the event.
In the model attached here this seems to work. However, in addition I would like to calculate the fraction of the population in this cohort which survives. For this reason I should have a variable which retains the initial value of this cohort. This I don't manage.

Note, that the model presented here is very basic. I just wanted to understand (and control) the mechanism. For this reason I put many issues in the model entity.

Thanks and regards

Model SMR3 contains the questionable variable and does not work, SMR4 is running.
CohortPop2 test SMR3.zip
(12.33 KiB) Downloaded 6 times
CohortPop2 test SMR4.zip
(12.03 KiB) Downloaded 2 times

Posts: 1794
Joined: Wed May 24, 2006 4:54 am
Location: Montana, USA

Re: A cohort model issue

Postby tomfid » Fri May 12, 2017 7:46 pm

How about putting the initial value into a stock ("original population" or similar) that persists?
Advice to posters (it really helps us to help you)

Blog: http://blog.metasd.com
Model library: http://models.metasd.com
Bookmarks: http://delicious.com/tomfid/SystemDynamics


Senior Member
Posts: 51
Joined: Thu Nov 18, 2010 9:18 am

Re: A cohort model issue

Postby moudi » Mon May 15, 2017 6:18 am

Right. It works like this. Thanks for the hint.

Return to “Ventity”

Who is online

Users browsing this forum: No registered users and 1 guest