stepwise
Interactive environment for stepwise regression
Syntax
stepwise(X,y)
stepwise(X,y,inmodel,penter,premove)
Description
stepwise(X,y) displays an interactive tool(交互工具) for creating a regression model (回归模型)to predict the vector y, using a subset of the predictors given by columns of the matrix X.
stepwise函数是一个交互工具，它使用矩阵X的列向量组成的子集来建立一个对y进行预测的回归模型。
Initially, no predictors are included in the model, but you can click predictors to switch them into and out of the model.
初始运算时没有X的列向量在模型中，但是可以通过选择列向量使它们加入或者剔除出模型。
For each predictor in the model, the interactive tool plots the predictor's least squares coefficient as a blue filled circle. For each predictor not in the model, the interactive tool plots a filled red circle to indicate the coefficient the predictor would have if you add it to the model.
对于模型中的每个变量，将它们的最小平方系数画成蓝色的实心圆圈，对于没有选入模型的变量画成红色的实心圆圈，表示如果引入这个变量它所具有的系数。
Horizontal bars in the plot indicate 90% confidence intervals (colored) and 95% confidence intervals (black).
图中的水平线表示了90%的置信区间(彩色的)，和95%的置信区间。
stepwise(X,y,inmodel,penter,premove) specifies the initial state of the model and the confidence levels to use. inmodel is either a logical vector, whose length is the number of columns in X, or a vector of indices, whose values range from 1 to the number of columns in X, specifying the predictors that are included in the initial model. The default is to include no columns of X.
这一段用来说明stepwise函数的各个参数的意义。其中X为自变量矩阵，y为因变量矩阵，inmodel可以为一个逻辑向量，它的长度为X中列向量的个数或者说变量的个数；也可以一个序列向量，它的取值范围为1－X中列向量的个数，用来指定模型中的初始变量，默认值是没有选取任何X的列向量。
penter specifies the maximum p-value that a predictor can have for the interactive tool to recommend adding it to the model. The default value of penter is 0.05. premove specifies the minimum p-value that a predictor can have for the interactive tool to recommend removing it from the model. The default value of premove is 0.10.
penter为选入标准的显著水平，默认值是0.05，premove为剔除标准的显著水平，默认值为0.10。
The interactive tool treats a NaN in either X or y as a missing value. The tool does not use rows containing missing values in the fit.
英语水平不太好，整个函数的意思大概明白，有几次参数的说明不知道理解的对不对(红色标注的)
请教一下这个inmodel参数我的理解不知道对不对？