# Selecione um modelo alternativo a partir de Regressão MARS®

Execute Módulo de análise preditiva > Regressão MARS®. Select Selecionar um modelo alternativo after the Gráfico r-quadrado vs número de funções base plot or the Desvio absoluto da média versus número de funções base plot.
###### Observação

Este comando está disponível com o Módulo de análise preditiva. Clique aqui saber mais sobre como ativar o módulo.

## Visão geral

Minitab Statistical Software produces results for the model with the best value of an optimality criterion. O critério é o erro mínimo quadrado ou o desvio absoluto mínimo, dependendo da sua escolha. O Minitab permite explorar outros modelos na sequência que levou à identificação do modelo ótimo. Typically, you select an alternative model for one of the following two reasons:
• The model that the analysis selects is part of a pattern where the criterion improves. Typically, you want to make predictions from a model with as much prediction accuracy as possible.
• The model that the analysis selects is part of a pattern where the criterion is relatively flat. One or more models with similar model summary statistics have much fewer basis functions than the optimal model. Typically, a model with fewer basis functions gives a clearer picture of how each predictor variable affects the response values. If the difference in prediction accuracy for a smaller model is negligible, you can use the smaller model to evaluate the relationships between the response and the predictor variables.
For example, the following plot accompanies results about the model with 20 basis functions. Other models in the sequence have similar R2 values.
The model with 10 basis functions has an R2 value that is almost as high as the model with 20 basis functions. Typically, a model with fewer basis functions gives a clearer picture of how each predictor variable affects the response values. If the reduction in prediction accuracy from a much smaller model is negligible, you can use the much smaller model to evaluate the relationships between the response and the predictor variables.
In addition to the criterion values for alternative models, you can also compare the complexity of models and the usefulness of different regions. Consider the following examples of reasons that an analyst chooses a particular model that does not sacrifice performance when compared to other models:
• The analyst chooses a smaller model that provides a clearer view of the most important variables.
• The analysis chooses a model because the basis functions are for variables that are easier to measure than the variables in another model.
• The analyst chooses a model because a particular region of the predictors is of interest.

## Perform the analysis

Selecione Selecionar um modelo alternativo na saída. A dialog box opens that shows a plot of the criterion against the number of basis functions and a table that summarizes the steps.

## Compare os critérios

To select an alternative model, select a point on the graph or a row in the table. Selecionar Exibir resultados para criar os resultados desse modelo.

Once you display the results, you can select Predição to make predictions from the model. For more information, go to Predizer novos resultados para Regressão MARS®.

###### Dica

Para comparar a saída de duas análises diferentes relatórios, clique com o botão direito do mouse em Navegador e selecione Abrir em visualização dividida.