poisson_reg() is a way to generate a specification of a model
before fitting and allows the model to be created using
different packages in R or Stan. The main
arguments for the model are:
penalty: The total amount of regularization
in the model. Note that this must be zero for some engines.
mixture: The mixture amounts of different types of
regularization (see below). Note that this will be ignored for some engines.
These arguments are converted to their specific names at the
time that the model is fit. Other options and argument can be
set using set_engine(). If left to their defaults
here (NULL), the values are taken from the underlying model
functions. If parameters need to be modified, update() can be used
in lieu of recreating the object from scratch.
poisson_reg(mode = "regression", penalty = NULL, mixture = NULL) # S3 method for poisson_reg update( object, parameters = NULL, penalty = NULL, mixture = NULL, fresh = FALSE, ... )
| mode | A single character string for the type of model. The only possible value for this model is "regression". |
|---|---|
| penalty | A non-negative number representing the total
amount of regularization ( |
| mixture | A number between zero and one (inclusive) that is the
proportion of L1 regularization (i.e. lasso) in the model. When
|
| object | A boosted tree model specification. |
| parameters | A 1-row tibble or named list with main
parameters to update. If the individual arguments are used,
these will supersede the values in |
| fresh | A logical for whether the arguments should be modified in-place of or replaced wholesale. |
| ... | Not used for |
An updated model specification.
The data given to the function are not saved and are only used
to determine the mode of the model. For poisson_reg(), the
mode will always be "regression".
The model can be created using the fit() function using the
following engines:
R: "glm" (the default), "glmnet", "hurdle", or "zeroinfl"
Stan: "stan"
Engines may have pre-set default arguments when executing the model fit call. For this type of model, the template of the fit calls are:
poisson_reg() %>% set_engine("glm") %>% translate()
## Poisson Regression Model Specification (regression) ## ## Computational engine: glm ## ## Model fit template: ## stats::glm(formula = missing_arg(), data = missing_arg(), weights = missing_arg(), ## family = stats::poisson)
poisson_reg() %>% set_engine("zeroinfl") %>% translate()
## Poisson Regression Model Specification (regression) ## ## Computational engine: zeroinfl ## ## Model fit template: ## pscl::zeroinfl(formula = missing_arg(), data = missing_arg(), ## weights = missing_arg())
poisson_reg() %>% set_engine("hurdle") %>% translate()
## Poisson Regression Model Specification (regression) ## ## Computational engine: hurdle ## ## Model fit template: ## pscl::hurdle(formula = missing_arg(), data = missing_arg(), weights = missing_arg())
poisson_reg() %>% set_engine("glmnet") %>% translate()
## Poisson Regression Model Specification (regression) ## ## Computational engine: glmnet ## ## Model fit template: ## glmnet::glmnet(x = missing_arg(), y = missing_arg(), weights = missing_arg(), ## family = "poisson")
poisson_reg() %>% set_engine("stan") %>% translate()
## Poisson Regression Model Specification (regression) ## ## Computational engine: stan ## ## Model fit template: ## rstanarm::stan_glm(formula = missing_arg(), data = missing_arg(), ## weights = missing_arg(), family = stats::poisson)
poisson_reg()#> Poisson Regression Model Specification (regression) #># Model from Agresti (2007) Table 7.6 log_lin_mod <- poisson_reg() %>% set_engine("glm") %>% fit(count ~ (.)^2, data = seniors) summary(log_lin_mod$fit)#> #> Call: #> stats::glm(formula = count ~ (.)^2, family = stats::poisson, #> data = data) #> #> Deviance Residuals: #> 1 2 3 4 5 6 7 8 #> 0.02044 -0.02658 -0.09256 0.02890 -0.33428 0.09452 0.49134 -0.03690 #> #> Coefficients: #> Estimate Std. Error z value Pr(>|z|) #> (Intercept) 5.63342 0.05970 94.361 < 2e-16 *** #> marijuanayes -5.30904 0.47520 -11.172 < 2e-16 *** #> cigaretteyes -1.88667 0.16270 -11.596 < 2e-16 *** #> alcoholyes 0.48772 0.07577 6.437 1.22e-10 *** #> marijuanayes:cigaretteyes 2.84789 0.16384 17.382 < 2e-16 *** #> marijuanayes:alcoholyes 2.98601 0.46468 6.426 1.31e-10 *** #> cigaretteyes:alcoholyes 2.05453 0.17406 11.803 < 2e-16 *** #> --- #> Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1 #> #> (Dispersion parameter for poisson family taken to be 1) #> #> Null deviance: 2851.46098 on 7 degrees of freedom #> Residual deviance: 0.37399 on 1 degrees of freedom #> AIC: 63.417 #> #> Number of Fisher Scoring iterations: 4 #>#> #> #> #> #> #>data("bioChemists", package = "pscl") poisson_reg() %>% set_engine("hurdle") %>% # Extended formula: fit(art ~ . | phd, data = bioChemists)#> parsnip model object #> #> Fit time: 33ms #> #> Call: #> pscl::hurdle(formula = art ~ . | phd, data = data) #> #> Count model coefficients (truncated poisson with log link): #> (Intercept) femWomen marMarried kid5 phd ment #> 0.67114 -0.22858 0.09648 -0.14219 -0.01273 0.01875 #> #> Zero hurdle model coefficients (binomial with logit link): #> (Intercept) phd #> 0.3075 0.1750 #>model <- poisson_reg(penalty = 10, mixture = 0.1) model#> Poisson Regression Model Specification (regression) #> #> Main Arguments: #> penalty = 10 #> mixture = 0.1 #>#> Poisson Regression Model Specification (regression) #> #> Main Arguments: #> penalty = 1 #> mixture = 0.1 #>#> Poisson Regression Model Specification (regression) #> #> Main Arguments: #> penalty = 1 #>