invest_3ed.pdf

The upper tail p value is calculated from the chi

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The (upper-tail) p-value is calculated from the chi-square distribution with ( r ± 1)( c ± 1) degrees of freedom. In R x Create a matrix of the observed counts and use chisq.test(matrix) To access the expected counts and (unsquared) chi-square contributions use chisq.test(matrix)\$expected and chisq.test(matrix)\$residuals. In Minitab x Choose Stat > Tables > Chi-Square Test for Association and specify the columns containing the table. Enter specify the columns with the two categorical variables or choose the Summarized data option and specify the columns containing the table. Click OK . x Under Statistics, check the Chi-square test, expected cell counts, and each cell’s contribution to chi-square. In Analyzing Two-way Tables applet x You can paste in raw data or the two way table. Remember to use one word variable names and categories. x Check the Show Table and Show F 2 output boxes.

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Chance/Rossman, 2015 ISCAM III Investigation 5.3 333 Investigation 5.3: Newspaper Credibility Decline With the proliferation of the Internet and 24-hour cable news outlets, it has become much easier for people to hear much more information, much more quickly. However, this has led to speculation that news organizations attempt to convey information before it has been properly verified in an effort to feed our impatience. USA Today reported that newspapers appear to be losing credibility over time (March, 2004). It cited a nationwide sample of 1,002 adults, 18 years or older, interviewed via telephone (under the direction of Princeton Survey Research Associates) during the period May 6-16, 2002. One of the questions asked was Please rate how much you think you can BELIEVE each organization on a scale of 4 to 1. On this four point scale, “4” means you can believe all or most of what the organization says. “1” means you believe almost nothing of what they say. How would you rate the believability of (READ ITEM: ROTATE LIST) on this scale of 4 to 1? The interviewer then asked this question for several different news organizations (e.g., USA Today, NPR, MSNBC). (a) Why is it important for the interviewer to rotate the list of organizations? When asked about “The daily newspaper you are most familiar with,” the percentage distribution of the 1002 responses in May, 2002 was: Believe all or almost all 4 3 2 Believes almost nothing ± 1 Can’t Rate 20% 39% 25% 9% 7% A similar study conducted in May, 1998 yielded the following results (981 responses). Believe 4 3 2 Cannot Believe ± 1 Can’t Rate 27% 36% 24% 7% 6% (b) Create a two-way table of counts to analyze the association between time and how people rate the believability of the daily newspaper they are most familiar with, among those who felt they could rate their daily newspaper. In other words, eliminate the “can’t rate” category from consideration. Also remember to use the “explanatory variable” as the column variable and that the observed counts do need to be integers.
Chance/Rossman, 2015 ISCAM III Investigation 5.3 334 Discussion: If we have independent random samples from several populations as in Investigation 5.1,

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