在Stata年度觀測值之間生成百分比變化？

Question

如何使用gen或egen命令生成不同年在Stata觀測值之間的百分比變化？例如，我對1990年觀測到2010年，每對支出不同的值，我想生成一個與1990 - 1991年，1991 - 1992年變化率的新的觀察等

Answer 1

//下面是與增長的另一項措施的例子：

clear 
set obs 100 
gen year = _n + 1959 
gen expenditure = _n^(1/3) + runiform() 
line expenditure year, yti("Synthetic data example") 

// From Statalist：

bys year: g expendituregrowth=100*(expenditure[_n]-expenditure[_n-1])/expenditure[_n-1] 

//另外：

gen expenditure_gr = (expenditure/expenditure[_n-1] - 1)*100 // growth rate for expenditure 
gen expenditure_bl = 100*expenditure/expenditure[1] // baseline growth rate for expenditure; base 100 = 1960 

line expenditure_gr year, yti("Growth rate") 
line expenditure_bl year, yti("Growth rate (base 100 = 1960)") 

//的expenditure_gr計算是什麼，我認爲你正在尋找。

//如果都能很好地形成你的數據，使用Stata的時間序列，並獲得輕鬆的增長速度：

tsset year, delta(1) 
cap drop expenditure_gr 
gen expenditure_gr = D.expenditure/100*L.expenditure