Question 715509: 19. Give an example of something having these distribution shapes: (a) bimodal, (b) approximately rectangular, and (c) positively skewed. Do not use an example given in this book or in class.
20. Find an example in a newspaper or magazine of a graph that misleads by failing to use equal interval sizes or by exaggerating proportions.
21. Nownes (2000) surveyed representatives of interest groups who were registered as lobbyists of three U.S. state legislatures. One of the issues he studied was whether interest groups are in competition with each other. Table 1–10 shows the results for one such question. (a) Using this table as an example, explain the idea of a frequency table to a person who has never had a course in statistics. (b) Explain the general meaning of the pattern of results.
22. Mouradian (2001) surveyed college students selected from a screening session to include two groups: (a) “Perpetrators”—students who reported at least one violent act (hitting, shoving, etc.) against their partner in their current or most recent relationship—and (b) “Comparisons”—students who did not report any such uses of violence in any of their last three relationships. At the actual testing session, the students first read a description of an aggressive behavior such as, “Throw something at his or her partner” or “Say something to upset his or her partner.” They then were asked to write “as many examples of circumstances of situations as [they could] in which a person might engage in behaviors or acts of this sort with or towards their significant other.” Table 1–11 shows the “Dominant Category of Explanation” (the category a participant used most) for females and males, broken down by comparisons and perpetrators. (a) Using this table as an example, explain the idea of a frequency table to a person who has never had a course in statistics. (b) Explain the general meaning of the pattern of results.
Answer by Positive_EV(69)   (Show Source):
You can put this solution on YOUR website! 19) A bimodal distribution is going to have some kind of underlying binary variable that will result in a separate mean for each value of this variable. One example can be human weight - biological sex is (mostly) binary and is a statistically significant indicator of how heavy a person is. A rectangular distribution will have an equal value under all parts of the curve; that is, it will be close to uniform. One possible example is the decimal part of a human's weight; that is, if a person weighs exactly 158.938 pounds, the variable of interest is .938. There's no reason for one value of this to be significantly more likely than any other. A positively skewed distribution has the bulk of its values below the mean, so that the median is less than the mean. Income is a good example of a positively skewed variable -- there will be a few people with extremely high incomes, but most people will have incomes bunched together below the mean.
That said, I don't know what examples are in your book. If you can't use those, follow the advice for each distribution and find something else that roughly fits that shape.
20) FOX News is a very good source for misleading graphs *nod*. Try, in particular, to find either the one with the unemployment rate during Obama's first term, or the one showing "job loss by quarter" starting in 2007. Those are both pretty "good" and should be easy to find via Google search. If this has to from a newspaper or magazine, I can't give you a specific graph, but you can use the ones I showed you as a comparison of what to look for.
21a) A frequency table is the list of all of the possible results that can occur during a random event, and each result's respective chance of happening.
21b) This is not possible without Table 1-10. I'm a statistician, not a psychic :P
22a) I don't know exactly how the definition changes given a different set of data, but this data set is broken into groups because the researchers expected there was an underlying variable that would make the two groups different.
22b) Again, this is difficult without the table. Would also make it possible for a better idea of what makes 21a different from 22a.
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