Understanding state space model

[martintburgess]

Hi @ellisp from annual leave,

No real issue here just hoping for a quick explanation. I'm trying to understand this line.

I understand that it is using the stan student_t sampling statement with 4 degrees of freedom to estimate the distribution of mu. What I'm struggling to understand is the indexing of mu. Why is it set from 2:n and then from 1:n-1?

I'm not super familiar with stan so if there's something fundamental I should know/read please direct me.

Many thanks,
Martin

[martintburgess]

On further investigation, I think I've got it - it's linking each day's mu to the previous day's mu to achieve the time series element.