by including NA in " " we transform it into a real missing value in an R factor vector
```
HIV_coded$bisexual<- factor(replace(HIV_coded$bisexual, HIV_coded$bisexual == "NA", NA))
```
-
Sometimes when you are running a regression model with variables that have different lengths, r will prompt with the following error message...
-
``` library(memisc) labels(anemia$anem)<-c("not anemic"=0, "anemic"=1) #library memisc ```
