Ch 24 Guiding Questions - Comparing Means

1. What graphical display should you start with when comparing means?

2. How do you find the standard error of the difference of two means?

3. How is finding a confidence interval for the difference of means similar to finding any confidence interval we have already studied?

4. What assumptions and conditions must we check?

5. How should you determine degrees of freedom?

6. It is never wrong not to pool, what does this statement mean in regards to comparing means?

the INVT Function on your calculator

Here is a YouTube video on how to create a program for InvT on a TI-83 or TI-83 Plus Calculator

Stats are Everywhere, even sometimes where you least expect.

Target targets pregnancies.

Chapter 23 Guiding Questions

1) What is the central limit theorem and why is it important in statistics?

2) What is a t distribution (Student's t-model)? What does a t distribution look like?

3) Why do we use a t-distribution for means instead of z?

4) What is a "degree of freedom" and why is this important with t-distributions?

5) How do you find a probability for a t-distribution in your calculator (Hint: for proportions we used normalcdf)?

6) How do you find a t critical value in the calculator?

7) What assumptions and conditions need to be met before we can use a t-model to run a hypothesis test or a confidence interval?

8) What should your conclusion be when interpreting a confidence interval for a t-distribution (give an example)?

9) What formula do you use when trying to figure out the sample size for a t-distribution? How can we find the t-critical value in this formula if we don't know our sample size?

Key to Review Sheet

Stats in the news, telling what ever story sounds more interesting.

http://articles.chicagotribune.com/2012-01-18/news/ct-perspec-0118-measure-20120118_1_poverty-rate-social-security-benefits-numbers

Chapter 22 Guiding Questions

1) When running a hypothesis test for the difference between two proportions, do we use standard deviation or standard error when finding our z-score, and what is the formula to find SD or SE?

2) Name and explain the assumptions and Conditions that need to be met in order to run a hypothesis test for differences between two proportions.

3) What is the formula for finding a two-proportion z-interval?

4) What is the null hypothesis going to be (usually) in a two proportion z-test?

5) What are the options for alternative hypotheses in a two-proportion z-test?

6) What is pooling and why do we use it when working with two-proportion z-tests?

7) Do we pool for a two-proportion z-interval? Why or why not?