## Additional Notes

- SAS represents missing values as "negative infinity" while Stata
represents missing values as "positive infinity". For example, within Stata,
numbers are ordered like this
all nonmissing numbers < . < .a < .b < … < .z

In SAS the order is reversed.

- Both SAS and Stata represent dates in a similar way, as the number of days before or since Jan 1 1960. So the date Jan 2 1960 is represented as a 1 in both SAS and Stata.
- SAS permits you to have multiple active data files at once, while Stata only permits one active data file (in memory) at once.

## Web notes

- You can view and download the hsb200.txt file here.