1.) Complete the "methods of data collection" take home test! (Also sent out via Remind).
2.) STUDY, STUDY, STUDY! Your take home test got you started on studying, but here are some more options so you're ready for your A tomorrow....
- Format of test:
- 15 matching vocab
- 9 multiple choice
- 3 open ended (2 of the 3 have parts abc)
- Be sure you know how to write a procedure for a cluster, stratified, or simple random sampling method
- Know the similarities and differences between the sampling methods, as well as the advantages of each
- Grade your classwork from today! ("Pop Quiz! Sampling MC" Packet). Here's the key:
- 1.) D
- 2.) D
- I hate this question. It's a tough one...
- The most common incorrect answer is "A." A is incorrect because when we think about bias, we're thinking about our sample being biased; many students choose A because of the fact that "80% of eligible voters actually did not vote in the last election," but this 80% is not referring to our sample of 1500 voters.
- We can't really choose E because we have no idea how our 1,500 voters were selected, so we don't really know if undercoverage is an issue; we also do know that the sample was collected randomly, which makes it less likely that undercoverage is a problem.
- The answer here is D because when people are asked, "Did you vote last year?" people, for whatever reason, often feel pressured to (maybe lie and) say yes. Picture walking up to someone and saying, "Did you vote in the last election?"
- 3.) E
- 4.) B
- For this question we should be able to recognize that we have a stratified sample, so no, this is not a simple random sample, which leads us to A,B, and C. From there, rather than trying to determine which statement is true/correct, I would try to use "process of elimination" and instead determine which two (of A,B,C) are definitely false, and whatever's left is your answer.
- In a simple random sample not only should each individual person/thing have the same chance of being chosen at any given time, but each sample or combination of people/things should be equally likely--which is not the case for this scenario.
- 5.) E
- Remember that what we assign is a factor. A blocking variable is not assigned, blocking is when we group people/things based on some existing characteristic, not based on something assigned.
- 6.) D
- 7.) B
- 8.) B
- 9.) A
- 10.) B
- Complete the experimental design extra practice (labeled as Stamp with the date 1/24/18) provided in class (or below) and check your answers!
- a.) Blocking Variables = gender and dying of hair (people are first grouped as male/female, as well as grouped (blocked) by whether they dye their hair or not, and then treatments (shampoo formula) are assigned from there.
- b.) Factor = what we assign = shampoo formula
- (2 levels, new or old shampoo, and since there is only one factor the levels = treatments = new shampoo group and old shampoo group)
- b.) Response Variable = what we measure = hair condition rating using a scale of 1-5
- Many students often give a generic answer that is more based on the intent of the experiment, like "effectiveness of shampoo," but remember the response variable is specifically what we are measuring (in this case, to determine the effectiveness of each shampoo formula)
- c.) This experiment is at least single blinded because the independent evaluators who determine the hair condition ratings are unaware what shampoo each individual used. For this to be double blinded we would have to make sure that the new and old shampoo formulas look, smell, feel, taste, etc. exactly the same so that no person can determine which formula they were assigned. If we added a control group we would also want to use some type of placebo shampoo, a fake shampoo that does nothing but looks exactly like the new/old shampoo so that none of the participants know what treatment group they are in.
- d.) Random assignment of treatments is important so that we can try to minimize bias and avoid the effects of any confounding variables that we may not have been aware of. If we randomly assign treatments within each block then, on average, the treatment groups within each block will "look similar" in terms of the people in those groups and will allow us to better compare (and establish a cause/effect relationship between shampoo type an hair quality rating.)
- More questions to consider:
- Could you diagram this experiment to fully outline the process?
- Describe a procedure for randomly assigning treatments with this blocked design.
- (Feel free to send me your answers if you try these and want me to check!)
- Look over your two vocab quizzes so you're ready for the (15) vocab matching questions on tomorrow's test!
- Vocab list = chapter 12 vocab quiz + chapter 13 vocab quiz
- Review your past stamps--many of these have the correct answer circled if you made a mistake, or, if you didn't have a chance to do some of the questions use them for extra practice! Feel free to send me your answers via Remind if you'd like me to check them!
- Do some more free response!
- Finish the 2004B #2 free response from class yesterday (about the dining halls) and score your response!
- Do the extra credit free response on the back of that question!
- Complete AND SCORE the 2008 Free Response (on the back of today's dining hall question)!
- 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!
