See below for an extra credit homework opportunity!
Tonight please complete and grade the "Writing About Bias" practice provided in class (or below).
YOU MUST USE THE ANSWERS BELOW TO GRADE YOURSELF--MAKE ANY CORRECTIONS AND/OR RECORD SOME NOTES ON YOUR RESPONSES--TO EARN CREDIT!
- For the record, that means if you just copy the answers you'll have nothing to correct and you'll have to get a 0. Don't do that. :)
Writing About Bias Answer Key:
- a.) Response Bias: The wording "Given the real-world context and clear application to the real world..." would lead people to respond "yes, Stat is more useful," and as a result this response (yes) would likely be over represented in our sample.
- Be sure to reference the specific wording in the question that is problematic (for any description of response bias)
- Context
- b.) Voluntary Response Bias: This data was collected using a voluntary response sample (online poll) rather than using a randomly collected sample; as a result, students who have the strongest opinions about the usefulness of Statistics are more likely to respond and are likely over represented in our sample.
- Connect to the sampling method (voluntary response sample)
- Be concise here, and be sure to use context--don't just say "those with strong opinions are over represented, be sure to tie that to this context.
- c.) Non-response Bias: For this poll, only 20 of 47 students responded to the survey question, and the 27 students who did not respond may have different opinions about the usefulness of Statistics than the 20 students who did respond.
- Don't just say "some people did not respond"-- extend to comment on the fact that those who did not respond may have a different opinion about ____ than those (20) who did respond
- Context! In this example we can use specific numbers of people who did/did not respond
- d.) Undercoverage: This sample was collected using an online poll on the class blog, and so any students who did not go to the blog did not have an opportunity to respond. It is possible that the students who do not think Statistics is useful are less likely to go to the blog, and so our sample may over represent students who do think Stat is useful, as they are potentially more likely to go to the blog and vote on this poll.
- Comment on who didn't have an opportunity to respond as a result of this method...
- Why does that matter? Connect "the people who didn't have a chance to respond" to a potential opinion about the usefulness of Statistics
Extra Credit Homework Opportunity: DUE FRIDAY!
Complete AND SCORE the 2008 Free Response (on the back of today's dining hall question)!
- This is extra credit AND a great way to review for Friday's test!
- Here's the link to the scoring rubric:
- And here's a link to the questions if you need it -- #2 is the extra credit question!
Today's Class Recap (delay schedule):
- Chapter 12 Vocab Quiz
- If you were out today you will do the quiz to start class tomorrow instead of our stamp!
- Writing About Bias (Practice)
- Completed 2004B Free Response (about the quality of food at dining halls for a given college campus)
- Friday = Unit Test (Methods of Data Collection)
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