PS296 Chapter Notes - Chapter 14: Null Hypothesis, Sampling Distribution, Standard Deviation
STATS CHAP 14: INDEPENDENT SAMPLES
Terms to remember:
Sampling distribution: the distribution of a statistic over repeated sampling
Standard error: the standard deviation of the sampling distribution of a statistic
t distribution: sampling distribution of the t statistic when the null hypothesis is true, central t
dist.
-most common use of the t test is to test the difference between the means of two independent
groups
-two sample means of independent groups will almost always differ by a small amount, what
matters is whether that difference is sufficiently large enough to justify the conclusion that the
two samples were drawn from different populations
-assumption that the populations from which the data are sampled are normally distributed is a
required assumption for the t test
Distribution of Differences Between Means:
Null hypothesis: H0: μ1 – μ2 = 0
-μ1 is mean of one population, μ2 is mean of second population
-the sampling distribution of differences between means is the distribution of the differences
between means over repeated sampling from the same populations (Xbar1 – Xbar2 or μ1 - μ2)
