ABSTRACT
There are two main areas of statistics: measuring things, especially measuring relationships between variables; and estimating how likely it is that the measure gotten could have occurred by chance. This chapter examines the second. The general procedure to calculate probability that a given result could have occurred by chance is the same procedure used in calculating the odds of any event happening. The statement one wishes to make about a relationship is not directly tested. Instead, its opposite is inserted, which is called the null hypothesis. In using the null hypothesis a single alternative is chosen, which negates all possible true values that would be consistent with the statement. A sampling distribution embodies all the assumptions made in a test, including the null hypothesis. A sampling distribution is a list of the probabilities that each possible event will happen. The chapter tries to give some idea of the general logic of inference.
