计算系数

Question

Question to be answered

有谁知道如何解决这个问题附着在两行代码？我相信as.matrix会创建一个矩阵，X，然后使用X %*% X,t(X)和solve(X)来获得答案。但是，它似乎并没有工作。任何答案都会有所帮助，谢谢。

Answer 1

我会建议使用read.csv代替read.table

这将是有益的，你走过去的两个功能在这个线程的区别：基于@kon_u的答案read.csv vs. read.table

df <- read.csv("http://pengstats.macssa.com/download/rcc/lmdata.csv") 
model1 <- lm(y ~ x1 + x2, data = df) 
coefficients(model1) # get the coefficients of your regression model1 
summary(model1) # get the summary of model1 

Answer 2

，这里是一个用手做的例子：

df <- read.csv("http://pengstats.macssa.com/download/rcc/lmdata.csv") 
model1 <- lm(y ~ x1 + x2, data = df) 
coefficients(model1) # get the coefficients of your regression model1 
summary(model1) # get the summary of model1 

### Based on the formula 
X <- cbind(1, df$x1, df$x2) # the column of 1 is to consider the intercept 
Y <- df$y 
bhat <- solve(t(X) %*% X) %*% t(X) %*% Y # coefficients 
bhat # Note that we got the same coefficients with the lm function