# Tracker in Markov cohort

Hi all! I would like the event probabilities and costs to vary based on the time a medical device has been in use, with the usage time reset when the device is replaced. The tracker was tested in the model, whereas this cannot function normally in the Markov cohort and Tornado diagram (the value always used the initial value of the tracker). How do I make the Markov cohort and Tornado diagram function normally?

Example 1:

{T} DeviceA = DeviceA+1

Probability of Failure: DeviceFailure[DeviceA]

Example 2:

{T} InFail_DeviceA = InFail_DeviceA+1

{T} AgeInFail_DeviceA = if (InFail_DeviceA=1;Age;AgeInFail_DeviceA)

if (AgeInFail1_DeviceA>2;cDeviceA;0)

Thanks for helping!

## Comments

Andrew MunzerIf you use trackers, then you must run Microsimulation for all analyses, including...

So you can still run Tornado analysis. Just check the box to run Microsimulation for each model calculation within the context of the Tornado diagram.

Sincerely,

Andrew

Ting-Hsuen LinHi Andrew,

Thanks for answering!

I tried the Microsimulation, but the new problem is:

Formula: if(_stage=0;pExp1;pExp2)

Both the pExp1 and pExp2 are constant.

For example: in stage 0, the probability is 0.001 in Microsimulation 1, but it is 0.004 in Microsimulation 2.

Tracker in forward nodes: if(_stage=0;pExp1;pExp2)

Node1: InFail=InFail+1

Node2: if(InFail=1;Age;AgeInFail)

Trans Cost: if (AgeInFail>5;cDevicce+cSurgery;cSurgery)

Thank you for your assistance.

Andrew MunzerI cannot examine the calculations above without the model. I think it's best to make your request in a support ticket rather than a forum. That way you can send the model and point to what you think is not working correctly. You can email the question and model to support@treeage.com.

You can use trackers anywhere in the model including Trans Cost.

Andrew

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