Weekend HW x2

**AP REGISTRATION FORMS DUE! If you didn't get your in be sure to have it Monday!**

If you were out Thursday you must make up the quiz you missed Monday at the start of class (while the rest of us do our stamp)!

You have two homework assignments, both of which will be checked on Monday:

Assignment #1.) Complete AND SCORE the 2013 AP Free Response #2. 

• You will only be given credit if you complete the FR, score it, AND write a few notes/bullets explaining why you got the score you did...anything else will earn a 0!
• For example, if the rubric says you would earn a "P" (partially correct), then provide some notes that explain what you would've needed to add to earn an E!
• Here is the link to the scoring rubric:
• 2013 Scoring Guidelines (scroll down to #2)! Click ME!
• For part a:
• Question A asks how using the first 500 students who enter the football stadium to estimate the % of students who are satisfied with the appearance of the school's buildings might be biased....
• We have not talked about bias yet, but you got this...
• Write about the following for a:
• 1.) Why might the sample not represent the population in regards to feelings about the appearance of buildings/grounds? More so, what types of students (in regards to feelings about appearance of buildings/grounds) might be over (or under) represented with this sample?
• 2.) How does this connect to estimating the % (proportion) of students who are satisfied with the appearance of the buildings/grounds--would you expect this sample to over or underestimate this %? (connect back to your ideas from step 1 above)

Assignment #2.) Complete the "Ch. 12 HW: Identifying Sampling Methods" questions/worksheet provided in class (or below).

• Ignore the questions about bias for #'s 11, 12
• Check your answers! (posted below)
• GRADE YOUR HOMEWORK! Learning is about making mistakes, then using a sample solution to work backwards and figure out those mistakes you made! Learning is not about "getting it right on the first try," or just doing your homework and never checking your work!

Today's Class Recap:

• Stamp = AP MC
• Worked in groups on our "Chapter 12 Sampling Methods Investigation" (packet) to develop a procedure for all 7 sampling methods
• We developed a procedure for SRS yesterday (Thursday)
• Today groups designed procedures for methods 2-7
• If you were out you should (do your best to) complete this packet and write such procedures on your own--these serve as your notes for this chapter!
• If you try this and get stuck, I have some "hint cards" that give examples of each procedure in another context. You can email me for these (carofano.fm@easthartford.org) or check Remind (sent them out today!)

2013 Free Response: Check answers using the scoring rubric linked above, score your response, AND write a few notes/bullets about why you earned the score you did.

Ch. 12 HW: Identifying Sampling Methods: Check answers below--grade yourself!

Homework Answer Key:

11a.) Voluntary Response Sample

11b.) Cluster Sample

11c.) (Attempted) Census

11d.) Stratified Sample

11e.) Simple Random Sample (SRS)

12a.) Voluntary Response Sample/Convenience Sample

12b.) Voluntary Response Sample

12c.) Cluster Sample

12d.) Systematic Sample

12e.) Stratified Sample

13a.) Multistage Sample--combines elements of a cluster sample (choose three churches at random from 17), as well as a stratified sample (then choose 100 random members from those 3 churches)

• A "multistage sampling method" simply combines multiple methods (as described above)
• Remember, SRS is an inherent part of a cluster or stratified sample, so that (SRS element) does not make a method "multistage." 

13b.) Answers will vary, but ultimately, what could happen is that the members we randomly choose from the 3 randomly selected churches may not give a representative sample of the population of all church members in this city. The 3 churches we choose may not (and probably don't) represent all churches in this city.

15a.) Systematic Sample

15b.) This sample is NOT likely to be representative of all patrons at the park. With this method we only surveyed people who are waiting in line (already), and we did not survey any patrons who are not in line. We would definitely want to survey patrons who are not in line because it is possible that the reason they are not in line think the wait is too long. We want a sample that represents all people at the park, not just those in line for this coaster (who clearly don't mind the wait).

15c.) All people in line for this ride

27a.) This is a simple random sample (SRS).

• First, number the transactions (from the previous day) from 1 to 120.
• Next, use a random number generator to generate 10 random numbers IGNORING REPEATS (or without replacement).
• The supervisor should then recheck the 10 transactions that correspond to the 10 numbers randomly generated.

27b.) We would modify the sampling strategy by using a stratified sample--first we would group (stratify) the transactions by type (wholesale or retail), then take an SRS from each group (strata).

• First, separate the transactions based on their type--wholesale or retail.
• Next, for the wholesale group, number the wholesale transactions from 1-36.
• Use a random number generator to generate 3 random numbers, ignoring repeats.
• The supervisor should then recheck the 3 wholesale sales that correspond to these numbers.
• Now, for the retail group, number each transaction from 1-84. 
• Use a random number generator to generate 7 random numbers, ignoring repeats.
• The supervisor then rechecks the 7 retail sales that correspond to the 7 randomly generated numbers.

*Note: we DO NOT always have to take (sample) the same number of people/things from each strat; we want our sample to be representative of the population, so we want to sample proportionally from our strata. If 30% of the population is wholesale, we want 30% of our sample to be wholesale sales--which is why we choose 3 of these and 7 retail sales.