CHAPTER 8: POPULATION, SAMPLE S, And PROBABILITY Key Thrms Population --- Any complete set of observations (or potential observations). Sample --- Any subset of observations from a population. Random sampl --- A sample produced when all potential observations in the population have equal chances of being selected. Probabili y --- The proportion or fraction of times that a particular outcome is likely to occur. Independent outcome --- The occurrence of one outcome has no effect on the probability that the other outcome will occur. Conditional probability --- Probability of one outcome, given the occurrence of another outcome Additional rule --- Add together the separate probabilities of several mutually exclusive outcomes to find the probability that any one of these outcomes will occur. Multiplication rul --- Multiply together the separate probabilities of several independent outcomes to find the probability that these outcomes will occur together. Mutually exclusive outcome --- Outcomes that cannot occur together. Thxt Review Section I Populations may be or . A real population is one in which all observations are at the time of sampling. A hypothetical population is one in which all observations are at the time of . Often it is not convenient or even possible to include all observations in a research project. In such cases, a or subset of observations is taken. The size of the sample is partially determined by estimated among observations and by an acceptable amount of . In order to use inferential statistics, the analysis must be based on a sample. A sample is random, if at each stage of the sampling, the selection process guarantees that all remaining have chances of being selected