[R-sig-ME] PREDICTIONS from a PIECEWISE LINEAR (mixed) MODEL: THEY AIN'T LINEAR BETWEEN BREAK POINTS!!

[Ben Bolker]

On 11-03-18 08:42 AM, Federico Bonofiglio wrote:
> I Dears,
> if that wouldn't take u too much effort I'd like to ask for a swift opinion:
> 
> I have a alinear (mixed effect) model that I wish to run as a piecewise one.
> 
> When I predict the values Iget quite some odds and disturbing results:
> The predicted stright line after the break point is not straight at all,
> instead behaves like if it was a hig order polynomial or something
> similar!!!!
> 
> I attach the codes below, hoping someone can point me the mistake....
> 
> 
> I sincerely  express many thanks in advance ......
> 
> Federico Bonofiglio
> 

  You have not given us a *reproducible* example ...
  I would guess that you need   I(rt>15) rather than rt>15 in your formulae.

  good luck
    Ben Bolker