C. Mandell - Research2: Statistics

Fall, 2007

Study Guide 2

Comparing 2 means - Chaps 7 - 10

Chapter 7

How can we inspect two independent samples using stem-leaf plots?
What is the pooled standard deviation?
What is a sampling distribution for the difference between two means?
How does the pooled standard deviation related to the standard deviations of the two independent samples?
What is the standard error of the difference between two means?
Explain the difference between independent samples and dependent samples (repeated measure designs).
Which type of statistical procedure (independent or dependent) would you use with a between-groups design, a natural experiment, a matched design, a within-group design.
What do we mean by difference scores? When do we use them?
What is a sampling distribution for the mean of the differences?
How can we compute the standard error of the mean of the differences?

Chapter8 - Estimating confidence in a mean

How can we consturc a confidence interval for a single sample?
How can we construct a confidence interval for the difference between two means?
What does it tell us if the confidence interval contains a 0?
What is effect size?
How do we compute Hedges' g? (don't worry about Cohen's d)
What do we consider a small effect? Medium effect? Large effect?

Chapter 9: Estimating using Null Hypothesis Significance Testing

What does hypothesis testing tell us?
Distinguish between null and alternative hypotheses
What do we mean by "rejection" regions, "rejection" criteria?
What is the distinction between directional and non-directional hypotheses?
What do we mean by the "alpha level?"
What is a t-test for independent groups?
What do we mean by t-observed? T-critical?
What are directional and non-directional t-tests?
How does sample size effect significance level?
How do we conduct a t-test for a dependent samples (repeated measure or matched groups) design

Chapter 10 - Interpreting and announcing results