有一个面板数据
xtset province year
panel variable: province (strongly balanced)
time variable: year, 1952 to 2008
delta: 1 unit
我想运行xtgls 命令,可是为什么出来的是这样的:
. xtgls dfrjzc zfcj wnjh czsrfq czzcfq gdp dfrjsr mzdq zxxsbl province1-province29 t, panels(cor) cor(ar1)
note: province29 omitted because of collinearity
year is not regularly spaced or does not have intervals of delta -- use
the force option to treat the intervals as though they were regular
为什么啊???year 这个变量的间距是有规律的阿?不懂,求解