Item 8
This question will ask you to provide a line of missing code.
Given the following data set WORK.SALES:
SalesID SalesJan FebSales MarchAmt
------- -------- -------- --------
W6790 50 400 350
W7693 25 100 125
W1387 . 300 250
The following SAS program is submitted:
data WORK.QTR1;
set WORK.SALES;
array month{3} SalesJan FebSales MarchAmt;
<insert code here>
run;
Which statement should be inserted to produce the following output?
SalesID SalesJan FebSales MarchAmt Qtr1
------- -------- -------- -------- ----
W6790 50 400 350 800
W7693 25 100 125 250
W1387 . 300 250 550
A. Qtr1 = sum(of month{_ALL_});
B. Qtr1 = month{1} + month{2} + month{3};
C. Qtr1 = sum(of month{*});
D. Qtr1 = sum(of month{3});
为什么B这种方式求和就是空值呀?关于这种missing value的哪里有详细讲解呢?