Statistics is the science of collecting and analyzing numerical data gathered from a representative sample in order to infer the true mean or proportion of a population. The x-bar_ is the symbol (or expression) used for the sample mean statistics.
Base salary is a fixed amount of money paid to an employee by an employer in return for work performed. Base salary does not include benefits, bonuses or any other potential compensation from an employer.
Gross salary-total pay before any taxes have been taken out. Net salary-take home pay, after taxes have been taken out. Base is the minimum amount you will be paid--no commissions, bonuses, dividends. Gross is everything you're paid, including dividends, bonuses, and commissions.