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.
7 Causes for Eye Twitching. An eye twitch is an involuntary spasm of the eyelid muscle that often happens in the upper lid. The sensation, for most individuals, is that of a gentle tug on the eyelid but some others may experience the twitching to be more of a strong spasm forcing the eye to be completely closed before opening it again. The twitching can last from a few seconds to a few minutes and can come back unpredictably.