Stat 411/511
# Quiz 2 Study Guide

**Reading:** Sleuth: 1.3, 2.3, 2.4, 2.5, 3.1, 3.2, 3.3 & 3.4

**Optionally**: OpenIntro 5.4

Everything that was on Quiz 1 could also be on Quiz 2.

You should be able to explain the meaning, or identify the correct explanation, of the following terms:

- randomization distribution

Identify from a study description if causal inference is justified.

State the three facts about the sampling distribution of the difference in two sample averages, based on two independent random samples.

Identify correct statements of facts about the sampling distribution of the difference in two sample averages, based on two independent random samples.

Construct a 95% confidence interval, based on the two sample t-ratio, given sample statistics (sample averages, sample standard deviations, and sample sizes)

Find a pooled standard deviation, given sample standard deviations and sample sizes.

Construct a two sample t-statistic given sample statistics (sample averages, sample standard deviations, and sample sizes) and a null hypothesis.

Given R output from a two-sample t-test:

- identify the total sample size (n1 + n2)
- interpret the result of the test in context of the study
- interpret the point estimate and confidence interval in context of the study

Write a three sentence statistical summary based on given output from a t procedure.

State the assumptions for the two sample t procedures.

From a study description identify whether a paired or two sample t procedure is appropriate.

State the assumptions for the randomization test.

Given a randomization distribution, and observed test-statistic, find a two sided p-value.