PROC表示SAS中的虚拟变量

Question

我在SAS中创建了一个虚拟变量，如果两个国家都是EMU的成员，那么在任何给定年份中，该值变为1，否则在该年份为0。

emu1=0;
if country1 in ("AUT","BEL","FIN","FRA","DEU","IRL","ITA","NLD","PRT","ESP") and year>1998 then emu1=1;
if country1 in ("GRC") and year>2000 then emu1=1;
emu2=0;
if country2 in ("AUT","BEL","FIN","FRA","DEU","IRL","ITA","NLD","PRT","ESP") and year>1998 then emu2=1;
if country2 in ("GRC") and year>2000 then emu2=1;
emu=0;
if emu1=1 and emu2=1 then emu=1;

现在，我希望看到变量gdp1的平均值，对于取值为emu=0的国家/地区和取值为emu=1的国家/地区。我该怎么做？

我知道我可以使用PROC MEANS：

PROC MEANS DATA=gravitydata mean MAXDEC=2;
VAR gdp1;
run;

但这显示了所有观察的平均值。

提前致谢。

Answer 1

只需添加class语句，即按指定变量分组。

PROC MEANS DATA=gravitydata mean MAXDEC=2;
CLASS emu;
VAR gdp1;
run;