ABSTRACT
This chapter explores various types of parameters and the statistical methods used to draw inferences about them. It deals with situations involving several variables or several populations. The population distribution for some variable is simply the proportion of individuals with each possible score on the variable. Another reason we need to consider the population distribution relates to the problem of statistical inference. The reason mathematical distributions are so useful is that they allow us to convey a great deal of information in very compact form. Moreover, the parameters needed to specify a particular distribution often have meaningful interpretations in their own right. This is particularly true of the parameters of the normal distribution: The mean is an indicator of the general magnitude of the scores, and the standard deviation is an indicator of how variable the scores are.
