conditional activation of outflow.

Use this forum to discuss any issues relating to Systems Dynamics and Systems Thinking.
Post Reply
Ryan
Junior Member
Posts: 6
Joined: Wed Jun 19, 2019 11:41 am
Vensim version: PLE

conditional activation of outflow.

Post by Ryan »

Hello everyone

I am modeling a surgeon's skills in a specific kind of surgery, she gains some skills in that specific kind of surgery if she performs one. she also loses some part of her skills in that kind of surgery if she doesn't have any interventions of that kind during 6 months.
the unit of time in my model is year and the time step is 0.015625. it means that she performs 64 surgeries every year (approximately one surgery every 6 days). so if there is no inflow to the stock of skills related to that surgery for 32 timesteps(=6 months), she must lose some skills.

suppose that I have the stock of that specific surgery, I want the outflow of my stock to get activated if there is no inflow during 32 time steps in a row.
I'll be thankful if anyone could help in modeling this part.
thanks in advance.
Administrator
Super Administrator
Posts: 4573
Joined: Wed Mar 05, 2003 3:10 am

Re: conditional activation of outflow.

Post by Administrator »

You can use SAMPLE IF TRUE to get the time at which the last inflow was. Then compare this to "time", if >= 6 months, reduce the stock of surgery.
Advice to posters seeking help (it really helps us to help you)
http://www.ventanasystems.co.uk/forum/v ... f=2&t=4391

Units are important!
http://www.bbc.co.uk/news/magazine-27509559
Ryan
Junior Member
Posts: 6
Joined: Wed Jun 19, 2019 11:41 am
Vensim version: PLE

Re: conditional activation of outflow.

Post by Ryan »

thank you so much
it really helped
Post Reply