Thursday HW

Tonight's (Thursday) HW will count as our first HW grade of the 4th quarter--so it counts double!

But first, a few reminders to wrap up the 3rd quarter:

• If you were out today please remember to bring your stamps tomorrow (or you'll earn a 0, and this is a biiiiig classwork grade)
• If you did not have the hw due today (crows problem and scored) you can show me tomorrow for full credit (check the previous blog post) 
• If you find any more stamps tonight bring those tomorrow too!
• If you have any tests (like Tuesday's) or quizzes to make up they must be done by 2:10 tomorrow

Thursday HW: Please complete and score the 2008 (Form B) Free Response provided in class (or below).

• 1/2 credit = complete the FR
• 1/2 credit = Score
• Use the answer key posted below (rather than the AP rubric) to grade your work
• Part (a) = "new stuff" (kinda)
• One "observation" is one piece of data--so the total number of "observations" we can afford is the sample size we can afford
• There are two ways to approach this...
• One way is to find the necessary sample size (n) to achieve the given a margin of error, then decide if we can afford that sample size...
• We'll use the same conceptual approach as finding n with proportions, but the formula for standard deviation is different (no more p's....)
• We can't find t* without sample size, so you'll just use z* for your critical value in this case
• Be sure to write a sentence that answers the question!
• Part (b) = think about your answer to (a)!
• Part (c): "statistical support' and "statistical evidence" imply a hypothesis test!
• Hypotheses, Conditions, Math, Interpret here....

Today's Class Recap:

• Stamp = Error Analysis for a t-test, t-interval
• Stamps were collected for the 3rd quarter
• HW Questions?
• What changes with our interval formula (with a t-interval)?
• The T-Distribution (Notes):
• What is the t-distribution? Why do we need it?
• How do we calculate degrees of freedom?
• How does df affect the shape of a t-distribution?
• When do we use a t test/interval for means?
• When do we use a z test/interval for means?
• Tomorrow's Focus: (top 2, middle left slides)
• Finding n with means (questions about 2008 part a + stamp)
• How do we find critical values for the t-distribution?
• How do we calculate p-values for the t-distribution?
• How do critical values/p-values compare for t distributions and the Normal model?
• What if we want to do a t-test/interval but the sample size is less than 20 and we're given the data set?

Here's Thursday's HW:

And here's the key to grade yourself after you complete the question: