Anthracite Anthracite Anthracite, often referred to as hard coal, is a hard, compact variety of coal that has a submetallic luster. It has the highest carbon content, the fewest impurities, and the highest energy density of all types of coal and is the highest ranking of coal. Anthracite is the most metamorphosed type of coal (but still represents low-grade metamorphism), in which the carbon content is between 92% and 98%. The term is applied to those varieties of coal which do not give off tarry or other hydrocarbon vapours when heated below their point of ignition. Anthracite ignites with difficulty and
Count data The Poisson distribution can form the basis for some analyses of count data and in this case Poisson regression may be used. This is a special case of the class of generalized linear models which also contains specific forms of model capable of using the binomial distribution (binomial regression, logistic regression) or the negative binomial distribution where the assumptions of the Poisson model are violated, in particular when the range of count values is limited or when overdispersion is present. Count data In statistics, count data is a statistical data type, a type of data in which the observations can