ARIMA model function returns <NULL MODEL> when ran on in an R Markdown on Posit Connect but not locally

[chriscarter945]

Hi there,

I've already asked this question on Posit Community's forum for Connect, but I suspect this behavior is a quirk of fable rather than Connect. Essentially, I have an R Markdown document that pulls in data from several APIs and generates forecasts using fable's ARIMA() function. When I run this document locally, all the code runs as expected. When I publish the document on Posit Connect, however, the ARIMA function returns empty model objects (forgive my possibly incorrect syntax). I've already confirmed that this is not an issue related to pulling in the data, as other features of the document indicate. What might lead to the ARIMA function returning a null model in one environment but not another?

[mitchelloharawild]

Hi, a NULL model occurs when there is an error in the estimation process. Any errors are converted into warnings, which would help to understand why you are getting a NULL model.

For an ARIMA model, my best guess is that it is failing due to not having urca installed (urca is used to perform the unit root tests that automatically identify d/D for ARIMA). Try installing urca on the remote system, and run the code again.

[chriscarter945]

Hi there,

That was the problem. Once I included library(urca) at the top of the script, it installed as part of the bundle published to the server. Thanks for your help!