Chapter Four


Displaying Percentages Graphically

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    Displaying Simple Part-Whole Relationships When percentages are part of a common whole, the usual way to display them is a pie chart. The pie chart has its share of problems as a graphical representation of data (particularly when people go all 3D on them), but the one thing a pie chart does is [...]


Standard Things Controlled For in Sociology, Medicine, Politics, Psychology & Economics

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When making comparisons between countries, climates, people, or anything else there are differences which can make a fair comparison difficult. Some disciplines talk about lurking variables, some talk about confounders — for the moment we are just going to talk about this stuff as the “things your comparison might need to account or control for.” [...]

sky bacon

Relative vs. Absolute Increases

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Let’s talk about risk for a second. And in particular, lets talk about bacon. If the article above is to be believed, eating two slices of bacon daily can increase your risk of pancreatic cancer by almost 20%. So here’s a simple question — if you eat bacon daily at those levels, what is your [...]


Stock vs. Flow

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Imagine a tank of water that has a pipe in and a pipe out. As water flows in, water also flows out. Ignore the flow rates on this diagram, and just think for a minute — if the water level in the tank is rising, what can we say about the inflow and outflow? The [...]

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. [...]