Categorical variables are also known as qualitative (or discrete) variables. These categorical variables can be further classified as being nominal, dichotomous or ordinal variables. Each of these types of categorical variable (i.e., nominal, dichotomous and ordinal) has what are known as categories or levels. These categories or levels are the descriptions that you give a variable that help to explain how variables should be measured, manipulated and/or controlled.
BetimolÂ® (timolol ophthalmic solution), 0.25% and 0.5%, is a non-selective beta-adrenergic antagonist for ophthalmic use. The chemical name of the active ingredient is (S)-1-[(1,1-dimethylethyl)amino]-3-[(4-(4-morpholinyl)-1,2,5-thiadiazol-3-yl]oxy]-2-propanol. Timolol hemihydrate is the levo isomer.
Fish fanciers are thus often unaware that, as of 2006, there are around 65 species classified within the genus Betta. A further source of confusion is that while the generic name Betta is italicized and capitalized, when used as a common name it is usually not capitalized.[4]. Yet, throughout the article and even the citation above, Betta is either lower-case or capitalized and infrequently italicized.