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.
While the base salary usually is a fixed amount per month, bonus payments more often than not vary depending on known criteria, such as the annual turnover, or the net number of additional customers acquired, or the current value of the stock of a public company.