Date: Dec 11, 2009 6:04 PM
Author: Skerbie
Subject: Re: [ap-stat] Question for AP Graders

Corey,

Thanks for the response, and I would agree. I require them to write it, but I feel as though I require them to write a lot more than what I see listed in the AP question scoring guidelines. "Good" or "bad," at this point, it boils down to a matter of efficient use of time on the AP exam. The time it takes to write "The sample of _____ makes up less than 10% of the overall population of _____ so we are willing to consider these individual observations independent of one another" takes a bit longer to write than the "nothing" that might be required, or even the "Independent observations ... CHECK!"


And while we're at it, I have at least one textbook that mentions the importance of this condition for proportions, but not for means ... is it not important for means as well? It would seem to me that it is for both, but what do I know ;)

Thanks,
Bill


----- Original Message ----

From: Corey Andreasen <candreasen@sheboygan.k12.wi.us>
To: Skerbie <skerbie@yahoo.com>; AP Statistics <ap-stat@lyris.collegeboard.com>
Sent: Fri, December 11, 2009 12:04:38 PM
Subject: RE: [ap-stat] Question for AP Graders

Bill,

I wouldn't use what appears on the exam rubrics as your guide for what is necessary to teach. You'll also see that, quite often, the rubric states that a description of 2 of the 3 (shape, center, and spread) will earn an E. But I wouldn't teach that.

I don't think the 10% condition has shown up on a rubric yet, but it is a necessary assumption if you are to use the SE formula taught in AP Stat. So students should be sure to check it. I try to teach students to give full correct answers, and I think it's a bad idea to try to guess what they'll be able to get away with!

Corey
____________________________________
Corey Andreasen
Sheboygan North High School
1042 School Avenue
Sheboygan, WI 53081




-----Original Message-----
From: Skerbie [mailto:skerbie@yahoo.com]
Sent: Fri 12/11/2009 7:30 AM
To: AP Statistics
Subject: [ap-stat] Question for AP Graders

Greetings,

I'm positive this question has come up on this list before, so my apologies - I do not have time right now to dig through the archives.

The 3rd edition of YMS makes a big deal out of stating "the sample makes up less than 10% of the overall population" as a check that observations within a sample can be considered independent of one another. However, I rarely see this mentioned as part of the check of assumptions/conditions on the AP scoring rubrics.

Can those of you who grade the AP exam address this? Is the above a statement they need to make for all inference procedures, or not?

Thanks again,
Bill Skerbitz





Frequently asked questions (FAQ) http://www.mrderksen.com/faq.htm
---
To unsubscribe click here:
http://lyris.collegeboard.com/read/my_forums/?forum=ap-stat
To change your subscription address or other settings click here:
http://lyris.collegeboard.com/read/my_account/edit




Frequently asked questions (FAQ) http://www.mrderksen.com/faq.htm
---
To unsubscribe click here:
http://lyris.collegeboard.com/read/my_forums/?forum=ap-stat
To change your subscription address or other settings click here:
http://lyris.collegeboard.com/read/my_account/edit