invest_3ed.pdf

# Of the 432 subjects asked the allow version 189

• 429
• 60% (5) 3 out of 5 people found this document helpful

This preview shows pages 244–247. Sign up to view the full content.

“forbid” version, 161 favored the forbidding of communist speeches. Of the 432 subjects asked the “allow” version, 189 favored allowing the speeches. Construct a segmented bar graph for these data and comment on whether you believe the p-value for this table will be larger or smaller than that in (e). Explain your reasoning. Analysis (a) The observational units in this study are the statistics students. The explanatory variable is the word choice in the question they responded to (categorical) and the response variable is whether their response was in favor of the speeches (“yes” with the allow question and “no” with the forbid question, categorical). (b) This was an experiment because the word choice in the question was randomly assigned to the students. Presumably the instructor mixed up the order of the questionnaires prior to passing them out to the students. This is important to equalize other variables between these two groups such as political inclinations and gender. The students did not know that there were two different forms of the questions, so the study was blind. If they had realized that the instructor was focusing on how they responded to the two words, they probably would have responded differently eliminating any subconscious effect of the word choice. (c) Two-way table, with the explanatory variable, word choice, as the column variable, and defining a “success” to mean that the student is in favor of such speeches:

This preview has intentionally blurred sections. Sign up to view the full version.

Chance/Rossman, 2015 ISCAM III Example 3.1 244 Allow Forbid Total Success 8 12 20 Failures 3 2 5 Total 11 14 25 (d) Here is the segmented bar graph, with word choice along the horizontal axis, and success defined as favoring the speeches (yes to the allow question and no to the forbid question). We see that most of these students were in favor of the speeches (80%). There was a slight tendency for those responding to the forbid question to appear more in favor (more likely to say no, do not forbid the speeches), 0.857 versus 0.727. However, the distribution within the bars look fairly similar and the association does not appear to be strong. (e) The null hypothesis will be that there is no effect due to wording of the question. So if S allow is the probability someone says “yes” to the allow question and if S forbid is the probability someone says no to the forbid question: H 0 : S allow S forbid = 0 and based on the prior research: H a : S allow S forbid < 0 Fisher’s Exact Test indicates how often we expect to see as few as 8 or fewer successes in the allow group (equivalently, at least as many as 12 successes in the forbid group). So if we define X to be the number in the allow group in favor of the speeches, X follows a hypergeometric distribution with N = 25, M = 20, and n = 11. The p-value will be P(X d 8). ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § ² ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § ² ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § ¸ ¸ ¹ · ¨ ¨ © § d 11 25 5 5 6 20 11 25 4 5 7 20 11 25 3 5 8 20 ) 8 ( X P = 0.3783
Chance/Rossman, 2015 ISCAM III Example 3.1 245 Confirming our calculations using R:

This preview has intentionally blurred sections. Sign up to view the full version.

This is the end of the preview. Sign up to access the rest of the document.
• Spring '14
• -STAFF

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern