1. Psychology 202a Advanced Psychological Statistics
September 28, 2017

2. The Plan for Today The Z test Assumptions The two-sample Z test
The t test

3. Using the central limit theorem for inference
The one-sample Z test
Hypothesis testing steps
Example: alpha=.05, two-tailed test

4. Using the central limit theorem for inference
s = 10, n = 25, M = 105
Two ways to make a decision: critical value or exact p-value
Demonstration in R

5. Assumptions of the Z test
Independent observations.
s is known.
Distribution is normal or sample is sufficiently large.
Problem: those assumptions are virtually never actually met.

6. The one-sample t test
Solution to not knowing s : substitute an estimate of the standard deviation.
Class example.
The t test in SAS.