# ddFixed

##### Auxiliary Functions for Fixed Effects

Functions used in formula of `ddhazard`

for time-invariant effects. `ddFixed_intercept`

is only used for the intercept.

##### Usage

`ddFixed(object)`ddFixed_intercept(random_intercept = FALSE)

##### Arguments

- object
expression that would be used in formula. E.g.

`x`

or`poly(x, degree = 3)`

.- random_intercept
`TRUE`

if a zero mean time-varying process should be included at as an additional term. Only relevant in stationary models. See the`type`

argument in`PF_EM`

.

##### Examples

```
# NOT RUN {
# we can get a time-invariant effect of `x1` by
# }
# NOT RUN {
ddhazard(Surv(stop, event) ~ ddFixed(x1), data)
# }
# NOT RUN {
# all of the calls below will yield the same result with a time-invariant
# intercept:
# }
# NOT RUN {
ddhazard(Surv(stop, event) ~ ddFixed_intercept() + x1, data)
ddhazard(Surv(stop, event) ~ -1 + ddFixed_intercept() + x1, data)
# }
```

*Documentation reproduced from package dynamichazard, version 0.6.6, License: GPL-2*

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