322 Final BST Questions and Answers Statistics - The most important goal of statistics is to infer an unknown quantity (e.g., height of a species of plant) of an entire population of plants based on sample data (a subset of observations from the population) Population - Entire collection of individual units that share a property or sets of properties from which you want to generalize knowledge about unknown quantities (observations) based on a sub-set of individual units (sample). Parameter - a quantity describing a statistical population Estimate or statistic - a related quantity calculated from a sample. Variable - any characteristic, number, or quantity that can be measured or counted. Height, weight, age, gender, business income and expenses, country of birth, capital expenditure, class grades and eye color are examples of variables. Observation units or Statistical units - the entity on which information is logged (e.g., one individual lake trout). Observation - contains all the values for the variables of interest such as the fork length and individual weight of an individual brook trout Categorical variables (qualitative variables) - describe membership in a category or group; characteristics of observations that do not have magnitude on a numerical scale Nominal or ordinal Nominal - Survival (alive or dead) Method of disease transmission (e.g., water, air, animal vector) Eye colours (amber, blue, brown, gray, green, hazel, or red), Breed of a dog (e.g., collie, shepherd, terrier) Ordinal - Life stage (e.g., egg, larva, juvenile, adult) Snake bite severity score (e.g., minimal, moderate, severe), Size class (e.g., small, medium, large). Numerical Variables (Quantitative) - characteristics of observations have magnitude on a numerical scale. Continuous or discrete