elasticsearch/docs/reference/ml/ml-shared.asciidoc

tag::dependent_variable[]
`dependent_variable`::
(Required, string) Defines which field of the document is to be predicted. 
This parameter is supplied by field name and must match one of the fields in 
the index being used to train. If this field is missing from a document, then 
that document will not be used for training, but a prediction with the trained 
model will be generated for it. It is also known as continuous target variable.
end::dependent_variable[]


tag::eta[]
`eta`::
(Optional, double) The shrinkage applied to the weights. Smaller values result 
in larger forests which have better generalization error. However, the smaller 
the value the longer the training will take. For more information, see 
https://en.wikipedia.org/wiki/Gradient_boosting#Shrinkage[this wiki article] 
about shrinkage.
end::eta[]


tag::feature_bag_fraction[]
`feature_bag_fraction`::
(Optional, double) Defines the fraction of features that will be used when 
selecting a random bag for each candidate split. 
end::feature_bag_fraction[]


tag::gamma[]
`gamma`::
(Optional, double) Regularization parameter to prevent overfitting on the 
training dataset. Multiplies a linear penalty associated with the size of 
individual trees in the forest. The higher the value the more training will 
prefer smaller trees. The smaller this parameter the larger individual trees 
will be and the longer train will take.
end::gamma[]


tag::lambda[] 
`lambda`::
(Optional, double) Regularization parameter to prevent overfitting on the 
training dataset. Multiplies an L2 regularisation term which applies to leaf 
weights of the individual trees in the forest. The higher the value the more 
training will attempt to keep leaf weights small. This makes the prediction  
function smoother at the expense of potentially not being able to capture 
relevant relationships between the features and the {depvar}. The smaller this 
parameter the larger individual trees will be and the longer train will take.
end::lambda[]


tag::maximum_number_trees[]
`maximum_number_trees`::
(Optional, integer) Defines the maximum number of trees the forest is allowed 
to contain. The maximum value is 2000.
end::maximum_number_trees[]


tag::prediction_field_name[]
`prediction_field_name`::
(Optional, string) Defines the name of the prediction field in the results. 
Defaults to `<dependent_variable>_prediction`.
end::prediction_field_name[]


tag::training_percent[]
`training_percent`::
(Optional, integer) Defines what percentage of the eligible documents that will 
be used for training. Documents that are ignored by the analysis (for example 
those that contain arrays) won’t be included in the calculation for used 
percentage. Defaults to `100`.
end::training_percent[]