Monte Carlo simulation not generating any results

Question

I'm attempting to run a monte carlo simulation with a product system I just created in a database. I have entered data quality scores and base uncertainty factors for all flows in the model, and have hit the "use as uncertainty factor" button to ensure that the correct geometric mean and standard deviation appear in the "Uncertainty" column for each flow. I have entered physical allocation factors for all co-products. When I calculate LCIA results using the lazy/on demand calculation type, I get estimated impacts as expected for tis product system, indicating to me that there are no data entry/provider linkage issues in the product system. When I run monte carlo simulations on the same product system with 100 iterations, no results are generated - not as in there are results and no uncertainty, as in I hit the start button, the progress bar fills, but the number beside "Results" stays at 0. Other potentially important details

- Monte carlo simulations run fine on other product systems within the same database

- I'm using openLCA version 2.6.1.

- I've got ~43GB of free space on the drive openLCA is operating on.

Any help would be appreciated as I've never seen something like this before when using openLCA

Answer 1

Maybe to find out the reason, some more questions: Which database type did you use, unit process, system process or library? Have you entered the uncertainties in exchanges of product flows that have a supply chain with impacts connected? Which uncertainty type did you chose, always log-normal for example? When you click on one of the exchange uncertainties and you run „test“, do you see the uncertainty statistics for 100 runs?

Comments

I'm using a unit process database (specifically ecoinvent 3.11 APOS). Uncertainties are entered in exchanges of product flows with connected impacts, evidenced by the fact that the exact same product system gives estimated impacts when choosing either of the "lazy/on demand" or "eager/all" calculation types. Uncertainty is defined as a log-normal distribution for all flows. When I click on exchange uncertainties and run "test", they show uncertainty distributions as would be expected.

I have edited my original question to include a screenshot of the output resulting from running a monte carlo simulation. As it shows, for some reason running the simulation just does not generate any results for this product system. Running uncertainty calculations on other, unrelated product systems works as expected.