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.
Random twitching of an eyelid, which happens in normal people, is called myokymia (an involuntary, spontaneous, quivering of a few muscle cell bundles within a muscle). Myokymia starts and stops spontaneously. In the eyelids, it can last a few minutes to a few days. It can be caused by stress, dry eyes, lack of sleep.