panel data regression in r

废话不多说，直接附上code
影片含有程序码详细解说，若有误再烦请告知，谢谢

library(plm)
data("Produc")
panel_data = pdata.frame(Produc, index = c("state","year"))

#选模型: within(固定),random(随机)  
#选依据: individual,time,twoways
固定 <- plm(pcap ~ pc , 
         model = c("within"), effect = c("time"),
         data = panel_data)

随机 <- plm(pcap ~ pc , 
         model = c("random"), effect = c("time"),
         data = panel_data)

phtest(固定, 随机)#<0.05 用within
model <- plm(pcap ~ pc , 
             model = c("within"),
             effect = c("time"),
             data = panel_data)
summary(model)