A SAS data set is exactly equivalent to the concept of a table (formally, a. âtupleâ) in the relational model. The programmer could use either data step MERGE or use a join. in PROC SQL. Which one to use can be a matter of personal preference. But if you learn each. method well, you can choose the best tool for each specific situation.
An eye twitch is an involuntary spasm of the muscles in the eyelid. Blepharospasm is the medical term for eyelid twitching. Eyelid twitching usually occurs every few seconds and lasts for a few minutes. It may come and go over a period of days or weeks. Sometimes the twitching results in the eye being held closed until the movement stops, but this is not always the case.
Eye Problems & Diseases / Eye Problems. An eyelid twitch, or blepharospasm, is a repetitive, involuntary spasm of the eyelid muscles. A twitch usually occurs in the upper lid, but it can occur in both the upper and lower lids. A persistent twitching means you should contact your eye doctor for a comprehensive eye exam.