If you have run with the specified inventory, it is expected to get different values of reorder level. And the default value of Horizon option is 12.
To obtain the identical reorder level for the stationary demand, you may try to run the following steps:
Do the policy optimization by OBJECTIVE=OPTPOLICY without inventory data
Set the inventory data based on this policy
Estimate KPIs by OBJECTIVE=PREDICTKPI
If you still have some questions or issues, please provide us your code and data sets.
For your second question,
since SS policy is used for OBJECTIVE=EVALISL, you can simply compute the reorder level as (order upto level – 1).
Thanks,
KDuck
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