【单选题】A data set that consists of a sample of individuals, households, firms, cities, states, countries, or a variety of other units, taken at a given point in time, is called a(n) _____.
【单选题】Assuming that the data set Company.USA has five or more observations, what is the result of submitting the following program? data work.getobs5(drop=obsnum); obsnum=5; set company.usa(keep=manager pay...
【单选题】For data transmission to be successful,sending and receiving devices must follow a set of communication rules for the exchange of information. These rules are known as( ).