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 twitches are commonly known as Blepharospasm, which is defined as the repetitive and rhythmic contraction of the eyelid muscles (which usually affects both eyes). Eye twitches are also less commonly known as Fasciculation, which is defined as the twitching or continuous movement of muscle fiber groups. Sometimes eye twitch is confused with Nystagmus, which is the jerking or jumping of the eye itself. This is an entirely different condition and an optometrist or ophthalmologist should be able to make a proper diagnosis after a full examination. Simply stated, eye twitches are muscle spasms and, like most muscle spasms, they generally have no long term side effects.