This chapter is pivotal. It connects the probability of the last two chapters with the statistical inference of Chapters 7 through 13. In this chapter we will be asking about the probability of getting a sample statistic-a sample proportion or sample mean-within given ranges of the comparable population parameter. For example, suppose we know that the population proportion preferring political candidate Smith is 0.55. That is, πS is 0.55. We will be able to say something like “given this population, if we take a random sample of 1000, the probability is 0.95 that the sample proportion, pS, will be within the range 0.55 ± 0.03.” Said differently, in repeated samples of 1000, the sample proportion preferring Smith, pS, will be in this range 95% of the time and will be outside this range 5% of the time.