Activity: Replot NASA Graph

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Using data from Wolfram Alpha or some other source, replot the NASA graph here either: 1. Controlling for inflation, 2. Tracking expenditure as a percentage of GDP, or 3. Tracking expenditure as a percentage of government spending. Defend your choice, and note any differences in the shape of the graph that result.

death penalty

Activity: Death Penalty Poll

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First, read How to Construct a Bogus Survey. Second, consider this poll from The Washington Post’s website. Walk through what would happen if you set up the poll in various different ways. Be ridiculous where it helps. For the moment, ignore issues of non-response and response bias. Name at least one strength and one weakness [...]

Stat Lit Chart of the Day

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Stat Lit Chart of the Day This chart could mean that the more education you get, the more you drink. What is another explanation for the increase in average annual expenditures on alcohol?


Base Rate, Revisited

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The following insight is an old saw of research on statistical intuition by now, but was revolutionary when Kahneman & Tversky came up with it in the early 70s. It is a good explanation of what goes wrong when we think about prediction. As you consider the next question, please assume that Steve was selected [...]

Critical Thinking is Part Intelligence, Part Attitude

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Critical Thinking is about more than intelligence: Even after controlling for differences in cognitive ability, reasoning performance correlated with degree of open-mindedness and epistemic flexibility (cultivating reflectiveness rather than impulsivity, seeking and processing information that disconfirms one’s belief, being willing to change one’s beliefs in the face of contradictory evidence). Further, these dispositions tended to [...]


Activity: Effect Sizes and Mind-Mapping

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Example from A Theory-Based Meta-Analysis of Research on Instruction by RJ Marzano: The next two techniques displayed in Table 7.2 employed the information processing function of idea representation.  Techniques that provided students with metacognitive strategies for using visual memory had an effect size of 1.04, indicating a percentile gain of 35 points.  Presumably, these strategies help [...]


A Note About Why Practice Matters

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From A. N. Whitehead’s An Introduction to Mathematics, some insight into why practice is important: “It is a profoundly erroneous truism, repeated by all copy-books and by eminent people when they are making speeches, that we should cultivate the habit of thinking of what we are doing. The precise opposite is the case. Civilization advances by extending [...]

Specificity and Sensitivity, Visual Explanation

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This is a great walk-through of the issues of sensitivity and specificity in medical test design and interpretation. It is a good supplement to the explanations in this text. Everyone that gets medical tests done or will get medical tests done (which, let’s face it, is everyone) should be familiar with these principles, but it’s often hard [...]


Associations and Mechanism: How Visa Predicts Divorce

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How Visa Predicts Divorce From TDB: Hunch then looks for statistical correlations between the information that all of its users provide, revealing fascinating links between people’s seemingly unrelated preferences. For instance, Hunch has revealed that people who enjoy dancing are more apt to want to buy a Mac, that people who like The Count on [...]


Activity Following “Stocks, Inflows, and Outflows”

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1. Consider the following issue: 17.1. A major controversy has occurred about apparent contradictions in biostatistical data as researchers try to convince Congress to allocate more funds for intramural and extramural investigations supported by the NIH. Citing improved survival rates for conditions such as cervical cancer, breast cancer, and leukemia, clinicians claim we are “winning [...]


Gas Prices and Cyclical Patterns

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When things have a seasonal cycle, it’s often difficult to make direct comparisons. Ideally you compare to last year this time, or the ten year average of this time last year, but what people really want is a sense of how high it will go. This article does a decent job with that — look, [...]


Distribution of Risk: J-Curves

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My new favorite term from epidemiology: J-Curve. Distribution matters, even with something as shades-of-grey as risk. For instance, yhere’s a lot of things that increase your mortality in a more-or-less linear way. The more you smoke, the greater your all-cause mortality risk, for example. This isn’t to say you increase your chance of death by [...]

Lifecycle Analysis: CFL vs. Incandescent Mercury Pollution

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From Lifecycle impact analyses, like the one shown above, are invaluable tools in making fair comparisons.  It’s easy, for example, to get hung up on the small amount of mercury in a CFL bulb, a percentage of which can escape into the environment if the bulb is crushed in a landfill. But the biggest contributor [...]

Mental Experiments and the Mancovery

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This is the new story out — it’s a mancovery! From Bloomberg: Men, who lost more than twice as many jobs as women during the worst economic slump since the Great Depression, have landed 88 percent of the non-farm jobs created since the recession ended in June 2009. The share of men saying the economy [...]

Mind the Edges: Unemployment by College Major

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In the COMPARABLE framework the “E” is for “Edges”, and part of the “question of edges” is whether there are significant subpopulations. In the case of unemployment of recent college grads, the answer is yes: The center would tell you only that the average unemployment for college grads is about 9%. But the lowest rates [...]

Longitudinal Analysis: SIDS and Prone Sleeping in Norway

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This is an amazing chart — sad in one way, but uplifting in another, because it shows how stats-informed public policy can make a difference. The chart represents the incidence of SIDS (“crib death”) in Norway plotted out against the rise and fall of parents that put their children to sleep on their stomach. (Which [...]

Farm Share of Food Dollar and Subgroups

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As we say in the COMPARABLE checklist, the story is often somewhere in the edges. Take this chart of the proportion of a food dollar which goes to the farmer vs. post-farm activities. At first it seems to show declining farm revenue as the the market bill (which includes everything from transportation to preparation) climbs: [...]


Surrogate Outcomes

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In medicine, researchers often rely on surrogate outcomes (also called surrogate endpoints). Take, for example, something like heart health. We know that a good ratio of good cholesterol to bad cholesterol is a predictor of heart health and increased longevity. So we come up with a pill that changes that ratio for the better. And [...]

Activity Following “Surrogate Outcomes”

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Focused question: While “surrogate outcomes” and “clinical outcomes” are terms generally used in medicine, the same concept can be applied to a wide range of disciplines. Come up with the equivalent of a “surrogate outcome” and its corresponding “clinically meaningful outcome” for each of the following disciplines: Education Economics/Economy Politics  


Activity: New Housing Starts Graph

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The following graph is from Architect Magazine. The caption reads: “The construction boom of the 2000s often cited as the reason for the boom in housing prices doesn’t break precedent—or break records. At a time when U.S. population growth was slower, the 1970s saw two housing booms that produced more housing starts than the 2000s. The high [...]


Questions: Student Loan Debt Surpasses Credit Card Debt

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Read the following comparison: Consumers now owe more on their student loans than their credit cards. Americans owe some $826.5 billion in revolving credit, according to June 2010 figures from the Federal Reserve. (Most of revolving credit is credit-card debt.) Student loans outstanding today — both federal and private — total some $829.785 billion, according to Mark [...]


Mental Experiment: Undocumented Immigrants in the University of California System

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Dream Act rally in Washington, D.C.   From the June 9 edition of Fox News’ The O’Reilly Factor: CARLSON: So, at University of California schools – just to get this in. O’REILLY: Right. CARLSON: In 2009, about 35 percent of the in-state tuition people or students were illegals. O’REILLY: Really? That’s an interesting stat, Carlson. [Fox News, The [...]


Example: Where’d the Productivity Go?

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The hourly compensation of a typical worker grew in tandem with productivity from 1948–1973. That can be seen in Figure A, which presents both the cumulative growth in productivity per hour worked of the total economy (inclusive of the private sector, government, and nonprofit sector) since 1948 and the cumulative growth in inflation-adjusted hourly compensation for private-sector [...]


Activity: Fluoridation and Decayed, Missing, and Filled Teeth

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From Promoting Oral Health:The Use of Salt Fluoridation to Prevent Dental Caries by Saskia Estupiñán-Day. This chart shows the incidence of decayed, missing, and filled teeth in children in a town that used fluoridation against a set of control towns that did not. 1. For the purposes of this graph, how was “fluoridation” defined? 2. Would this [...]


Activity: Rabbits

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The settler Thomas Austin released 24 wild rabbits on his Australian farm, called Barwon Park, in 1859, and some other Australian farmers later followed his example. Rabbits are sexually mature at about six months, and they have a 31-day gestation period. Given a favorable environment, rabbits can easily increase their population fourfold in a year. [...]


Activity: Law Salaries

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The graph above shows salaries of 2006 graduates of law school as measured in 2007. 1. The study did not include people out of work. How might the graph shape change if it included people out of work? Would the median salary be lower or higher? 2. Look up the term “bimodal distribution”. Does this [...]


Activity: Rent vs. Mortgage Cost

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Some people say that we couldn’t have known there was a real estate bubble. But quite a few economists pointed out well before the crash that the “price/rent” ratio — that is, the average cost of owning a house/apartment divided by the average cost of renting — was well outside of historical norms. This led economist [...]


Zero-day Comparisons

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Game of Thrones, Season 2 is getting illegally downloaded. A lot. In fact, it’s on track to be the most pirated show of 2012, and maybe 2011 as well: Maybe that’s interesting to you, maybe not. Here’s what’s interesting to me: notice the horizontal axis of the graph. What this represents is number of days [...]


Activity: UGC Graphic

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Apply the COMPARABLE checklist to the comparison “How much of a rule does UGC play in your purchasing decisions?” What are some strengths of the comparison? What might be a better comparison?L Look up the source of the infographic. How might the interests of the producer of the graphic affect the presentation of the information?


Activity: CEO Pay Infographic

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Via Click on the graphic to enlarge.   IN this graphic, the association is made that the more people were laid off at a company, the bigger the salary. That seems like we are rewarding incompetence! What might be a confounding factor? What should be taken into account to fix the comparison? Hint: ptgaeocfiszeoynmtp If such [...]


Activity: Safety of Banks vs. Credit Unions Infographic

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From   1. Use the Junk Charts Trifecta to evaluate this graphic: a. What issue does this graphic address? What questions does it try to answer? b. What does the chart say? c. What does the data say? 2. What information would you need to better evaluate these charts? How might you alter the measures [...]


Activity: Hidden Sugar Infographic

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From   First, a comment — note how nicely their sources are laid out. You don’t know what goes to what, but at least you have a starting point. Now, questions: 1. Source: Who is OnlineSchools? What’s their stake in this issue? Did they collect the data, or did someone else? 2. Look at comparison [...]


Activity: New Buildings Per Person

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Did overbuilding houses lead to the recession? Matthew Yglesias shows this graph to demonstrate that overbuilding wasn’t the problem: He explains: On the general subject of recession myths, here’s another statistical look at the myth that the speculative boom in land prices led to some kind of crazy amount of overinvestment in houses. What we [...]


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The COMPARABLE Checklist (suitable for printing!). This checklist can be applied to any numerical comparison, although not all items apply to every comparison. This is an abbreviated version of the checklist; the chapters of the text describe these elements in more detail. C:  Were appropriate comparison groups picked? Was like compared to like? O:  Were the [...]

europe and us

Activity: French Billionaires

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From Forbes: Bringing Up Bebe? No Thanks. I’d Rather Raise a Billionaire Quick: Name a French billionaire. Now name one who is self-made. A bit harder, non? According to the Forbes World’s Billionaires List, published today, France has sixteen billionaires. The U.S. boasts far more: 425. And a great number of those American billionaires, from Bill Gates (No. [...]

Proxies, Proxy Figures

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From At times of stress, we know that China’s GDP numbers can appear a little weird. In late 2008, we recommended a number of growth proxies to watch in case the GDP numbers became less reliable, including electricity production, freight traffic, and production of key industrial goods. All of these proxies suggested a deeper downturn [...]

Intention to vote

Activity: Intention to Vote

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Read the following poll results, then answer the questions. This is a poll that asks people how likely they are to vote in the 2012 election. 1. What is the cut-point for “Intends to vote”. How does it effect the results? How might changing the cut point change the results? 2a. This compares intent to [...]


Activity: Labeling Restaurant Food

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After nutritional labeling went into effect in New York City, a large sample of people were polled about how the label affected their behavior — 27% reported the new labels influenced their behavior, and 10% of people reported purchasing fewer calories as a result. However, when researchers looked at the average amount of calories purchased [...]


Readings: Comparing Cranial Size (from Cranioklepty)

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Morton’s findings, published in his Crania Americana (1839) and Crania Aegyptiaca (1844), were enormously influential in appearing to demonstrate, by means of his system, that there was a clear hierarchy in brain size between different peoples. At the top of his scheme was the European, followed by the American Indian, and then the African, just one short step above [...]

Activity: “Keeping Trash Out of the Landfill”

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Read the post, “Keeping_gameday_trash_out_of_the_landfill.” During the three recent football games listed (Iowa v. Cent. Michigan, Iowa v. Northern Iowa, and Iowa v. Iowa State) what was the percentage of food waste for compost of the total waste for each game? The article touts a nearly 60% recycling/composting rate following the Iowa vs. Northern Iowa game. [...]