SAS軟件：如何刪除具有五個以上零的因變量的觀察值

Question

我有一個消費者面板數據，每週在零售商店記錄支出。唯一標識符是家庭ID。如果花費超過五個零，我想刪除觀察值。也就是說，這個家庭在五週內沒有購買任何東西。一旦確定，我將刪除與家庭ID相關的所有觀察結果。有誰知道我如何在SAS中實現這個過程？謝謝。

Answer 1

我認爲proc SQL會很好。

這可以用一個更復雜的子查詢在一個步驟中完成，但它可能更好地分解成2個步驟。

1. 計算每個家庭ID有多少個零。

2. 過濾器僅包含具有5或更少零的家庭ID。

proc sql;
create table zero_cnt as
select distinct household_id,
sum(case when spending = 0 then 1 else 0 end) as num_zeroes
from original_data
group by household_id;

create table wanted as 
select * 
from original_data 
where household_id in (select distinct household_id from zero_cnt where num_zeroes <= 5); 
quit; 

編輯：

如果零必須是連續的，然後建立ID列表中排除的方法是不同的。

* Sort by ID and date; 
proc sort data = original_data out = sorted_data; 
by household_id date; 
run; 

使用滯後算子：檢查以前的支出金額。在LAG

此處瞭解詳情：http://support.sas.com/documentation/cdl/en/lrdict/64316/HTML/default/viewer.htm#a000212547.htm

data exclude; 
    set sorted; 
    by household_id;  
    array prev{*} _L1-_L4; 
_L1 = lag(spending); 
_L2 = lag2(spending); 
_L3 = lag3(spending); 
_L4 = lag4(spending); 

    * Create running count for the number of observations for each ID; 
    if first.household_id; then spend_cnt = 0; 
    spend_cnt + 1; 

    * Check if current ID has at least 5 observations to check. If so, add up current spending and previous 4 and output if they are all zero/missing; 
    if spend_cnt >= 5 then do; 
    if spending + sum(of prev) = 0 then output; 
    end; 
    keep household_id; 
run; 

然後，只需使用子查詢或匹配合並來去除「排除」數據集的ID。

proc sql; 
    create table wanted as 
    select * 
    from original_data; 
    where household_id not in(select distinct household_id from excluded); 
quit;