Something that will (hopefully) make you want to learn about probability & statistics

2

(for reasons greater than “my degree says I have to”)

Part I: Fact Check!

2006 – CBS reports that an appalling number of food poisonings happened in US school cafeterias in 2005...

733How horrid! But...

According to the CDC, there are 76 million food poisonings per year in the US.Assuming 300 million Americans eating, on average, 3 meals per day, the rate of food poisoning in America is about

76,000,000 0.0002, or 0.02%.300,000,000 3 365

2006 – CBS reports that an appalling number of food poisonings happened in US school cafeterias in 2005...

733

According to the US Census Bureau, there were approximately 75,800,000 children in school in 2005. Thus, the rate of food poisoning in school cafeterias was

733 0.00000005, or 0.000005%.75,800,000 180

...or, about 4000 times less likely than the general population.

In the first half of 2008, American drivers logged 30 billion fewer miles than in the first half of 2007.

As of 2011, there are 550 million people using Facebook . In the time it took you to read that last sentence, they uploaded 5000 photos.

The US uses almost a quarter of a trillion plastic beverage bottles each year.

The US has a national debt of just over 14 trillion dollars (as of 2011). By the time you finish reading this sentence, it will have grown by about $100,000.

100 species on earth become extinct every day.

1 billion people worldwide watched the 2006 World Cup Final.

(sources: World Resource Institute, Wade DeBral, TIME, Mark Zuckerberg, FIFA, CNN, Chris Jordan, Congressional Budget Office)

COCC blocks roughly 50,000 Spam emails a day.

Part II: Read deeply...and look carefully!

Anything wrong with this graph?

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old tuition new tuition

Tuition ($)

Part III: Correlation does not imply Causation!

Fact: Ice-cream sales are strongly correlated with crime rates.

Possible Conclusion: Therefore, higher ice-cream sales cause crime.

Alternate Conclusion: High temperatures increase ice-cream sales but also increase crime rates - perhaps by making people irritable or restless, or by increasing the number of people outside at night.

Historically, parents of daughters are more likely to divorce than parents of sons. If you have daughters, should you worry about divorce?

What could justify this correlation?

Possible Conclusion: In many species, stressed populations produce disproportionate numbers of female offspring (Why? I don’t know). Perhaps the stress came first, followed by the daughters (instead of the daughters first, then the divorce). Apparently, it’s a lot of work to insert testosterone!

Part IV: How Random!

Randomness in 30 darts thrown...spot the fake!

Don’t buy it?

Randomness in 200 flips of a coin...spot the fake!

Sequence #1HTHHHHHTTHHHHTTHTTHHTHTHTHHTTTHTHTTHHHHHTHHTHHTHTTHTHHHHHHTTHHTTHHTTTHHTHHTHTHTHTTHHTTHHTTHHTHTTTTTHTHHTTHTTHTHTHTHHHTHHTTTHHTTHHHTTTTHHTHHTTHTTTTHHHHTTTHTHHTTTTTHTTHHHHHTHTTTHHTHTHHTHTHH

HTTTHTHHTHTHT

Sequence #2HHTTTHTTHHHTHHHTHHTTHHHTHTTTHTTTHHTTTHHTHTTHHTTHHHTHTTTHHTTHTTTHHTHHHTTTHHHTTHTTHHHTHTTTHHHTTHHTHTHTTTHHTHHHTTTHTHTHHTHTTTHHTHHHTHHHTTHHTTTHHTHTTHHHTTHHTTHHTTTHTHTTTHHHTTHTHHTTHTTHHHTTTHTTH

HHTTTHTHTTT

Chance of at least a run of 6 in 200 flips 96%

Don’t buy it?...and what does this have to with my birthday?