PS296 Chapter Notes - Chapter 8: Null Hypothesis, Sampling Distribution, Statistical Hypothesis Testing
Null Hypothesis:
-can refer to the hypothesis that the difference between the two population means is zero, or null
(also called a nil null hypothesis)
-logic behind this is that we can never prove something to be true, but we can prove something to be
false
-null hypotheses provide us with the starting point for any statistical test
-we do not have a specific alternative research hypothesis in mind, and without one we cannot
construct the sampling distribution we need
-however if we start off by assuming H0 : mean = 100, we can immediately set about obtaining the
sampling distribution for mean = 100 and then, with luck, reject that hypothesis and conclude the
mean score is actually greater than 100 or less than
Test Statistics and Their Sampling Distributions:
-test statistics is a whole different class of statistics associated with specific statistical procedures and
has its own sampling distributions
-t, F, X2
-sampling distributions for test statistics can be obtained and used in essentially the same way as the
sampling distribution of the mean
t-Tests
-t tests are used to determine whether two samples were drawn from populations with the same
means
