seg | R Documentation |
Function used to define a segmented (stepmented) term within the segreg (stepreg) formula. The function simply passes relevant information to proper fitter functions.
seg(x, npsi = 1, psi = NA, est = NA, R = NA, fixed.psi = NULL, by = NULL, f.x = I)
x |
The segmented/stepmented (numeric) covariate |
npsi |
The number of breakpoints/jumpoints to estimate. Default to |
psi |
Numerical vector indicating possible starting value(s) for the breakpoint(s). When provided, |
est |
Possible vector (of length equal to |
R |
Matrix to constrain the slopes. If provided, it overwrites the matrix (which is built internally) coming from the specification of |
fixed.psi |
Possible fixed breakpoint values to be accounted for in addition to the estimated ones; |
by |
A possible factor meaning an interaction with the segmented term |
f.x |
an optional function meaning a function to apply to the covariate before fitting |
The function is used within segreg
and stepreg
to 'build' information about the segmented relationships to fit.
The function simply returns the covariate with added attributes relevant to segmented term
If any value is provided in fix.psi
, the corresponding slope difference coefficient will be labelled by *.fixed.*
. The slope
function will compute the 'right' slopes also accounting for the fixed breakpoints.
Vito Muggeo
segreg
##see ?segreg
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