# SAS MISS 的用法

2019.01.08 11:22 3257浏览

#### SAS Day 20: Miss function

There are two miss functions in SAS I really like, NMISS and CMISS.

#### Problem:

if we want to calculate the duration as aendt(Adverse Event End Date) — aestdt (Adverse Event Start Date). Ideally, we can use adurn=aendt-aestdt +1. However, in reality, we know there are high probabilities with missing AE dates.

Background Knowledge:

NMISS function is reserved for numeric variables.

MISSING and CMISS function can be used with either character or numeric arguments.

NMISS and CMISS count the number of arguments with missing values.

[caption id=“attachment_1385” align=“alignnone” width=“500”]

Engin_Akyurt / Pixabay[/caption]

#### Solution:

1. Basic Approach
``````if aendt^=. and aestdt^=. then adurn=aendt-aestdt+12
``````

2. NMISS function

``````if nmiss(aendt, astdt)=0 then
``````

What if we want the Adverse Event Duration Time of the Patients’ with AE ends up in hospitalization?

3. CMISS function

``````set ae;
if cmiss(aeshosp, aestdy, aeendt)=0
run;
``````

#### Summary:

Methods of selecting non-missing records:

1. x neq. , x neq “ “, Miss(x)=0
note: with Miss function, we don’t need to worry about the type of variables

2. NMISS: good for selecting multiple numbers of non-missing numerical variables.
e.g. nmiss*(x1, x2,….xn)=0*

3. CMISS: good for selecting multiple numbers of non-missing character or mixed variables.
e.g. cmiss*(subjid,* aestdy*,* aeendt*)=0*

Happy Studying!!! ❄

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