This preview shows pages 1–2. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: CHAPTER 6 SAMPLING DISTRIBUTIONS SPRING 2008 STA 3032 Random Sample : If n elements are selected from a population in such a way that every set of n elements in the population has an equal probability of being selected, the selection of such a set n elements is said to be a random sample. The probability distribution of a statistic is called a sampling distribution. The standard error of a statistic is the standard deviation of its sampling distribution. Central Limit Theorem : If X is the mean of a sample size n taken from a population having finite mean and finite variance 2 , then n X Z / - = is a random variable whose distribution function approaches that of the standard normal distribution as n. As n gets larger (30 or more), the sampling distribution of the sample mean approaches the normal distribution, and ) ( ) ( X E X E = = n X Var n X Var ) ( ) ( 2 = = n is the standard error (standard deviation) of X Example: Studies have shown that the supercooling temperature of terrestrial frogs frozen at -6...
View Full Document