From the course: Everyday Statistics, with Eddie Davila
The normal distribution is everywhere
From the course: Everyday Statistics, with Eddie Davila
The normal distribution is everywhere
- [Instructor] Perhaps when you were in school the instructor would put up the entire class' test results on a chart. Often it would look like a bell. In fact, they might have referred to it as the bell curve. Actually, you probably had a number of instructors that showed this to you. Maybe you even started to wonder if it was an academic conspiracy. Well, I'm here to tell you it's not a conspiracy. In fact, we don't just see bell-shaped distributions on test scores. They're everywhere. All around us. And while we might refer to this curve as the bell curve, statisticians refer to it as a normal distribution. And as I said, so many things in nature and society are normally distributed. If you measure the blood pressure of a large number of humans, the results will look like a bell curve. The temperature in London over the last 10 years. The sizes of watermelons grown in a certain state. The heights of NBA basketball players. Shoe sizes for women. The weights of newborn babies in Japan. When the number of observations is large enough, the data will resemble a normal curve. Now, not all normal curves are created equal. Some are tall and skinny. Some are wide and fat. And some are somewhere in between. And what's even more amazing, armed with the normal distribution and just a little bit of statistical know-how, you can estimate how common a single data point might be. Why? Well, when you have a normal distribution, about 68% of all data points will be within one standard deviation of the population average. 95% of data points will be within two standard deviations of the population average. And 99.7% of all data points will be within three standard deviations of the population average. So since you know that many things in nature, like blood pressure, are normally distributed, if you had the population's average blood pressure and you could calculate the standard deviation for the population, you would be able to see if someone's blood pressure was pretty normal, within one standard deviation of the average. Or maybe a huge outlier. That is, three or more standard deviations from the mean. As I said, the test score bell curve is not a conspiracy. And it's something you'll likely encounter in nearly any career. Take the time to get the basic statistics foundation that will help you discover the importance of the normal distribution.
Contents
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Political polls3m 14s
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Different sports, different stats4m 42s
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Test scores2m 59s
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Data collection2m 40s
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Birthdays in the USA3m 15s
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The house always wins4m 1s
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Wisdom of the crowd3m 12s
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The pay gap at Uber3m 58s
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Cancer survival rates4m 22s
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Television ratings4m 15s
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Historic stats stories4m 28s
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The one percent3m 58s
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New Year's Eve3m 28s
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Influenza3m 17s
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Winter is coming3m 11s
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The Super Bowl4m 39s
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Genetics3m 45s
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Relationships3m 48s
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The box office2m 39s
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Unemployment2m 41s
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Waiting in lines4m 29s
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Sleep2m 56s
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March Madness4m 43s
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Measuring what's important in business3m 28s
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Baseball4m 41s
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Income tax statistics1m 49s
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College waiting lists4m 26s
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The normal distribution is everywhere2m 53s
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Horse racing statistics3m 45s
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Statistics and the insurance industry2m 35s
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Restaurant statistics2m 43s
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Catching criminals with statistics2m 55s
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Getting directions from statistics2m 43s
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Lyme disease2m 55s
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Quality control in manufacturing2m 36s
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Zoo animal statistics2m 41s
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Earthquakes2m 54s
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Statistics of hunting2m 48s
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Transcontinental convoy2m 7s
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Moon landing3m 44s
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Summer movies2m 56s
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Reliability3m 47s
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Woodstock3m 44s
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Hurricanes2m 47s
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P-hacking2m 49s
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Salaries2m 51s
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Dow Jones3m
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Population3m 23s
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Epidemiology2m 55s
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Rock stars3m 44s
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Acceptance sampling3m 18s
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The value of my change4m 42s
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In-game win probabilities3m 39s
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Stock market ups and downs3m 18s
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Prohibition3m 30s
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Bayes' theorem4m 15s
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Divorce3m 35s
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The U.S. Census3m 26s
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English3m 8s
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Santa Claus3m 47s
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Parenting3m 6s
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Proportions of coins4m 53s
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Safe travel3m 23s
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Election polling methodologies2m 57s
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Is your data any good?3m 44s
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Storytelling with data2m 41s
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The middle of my data3m 21s
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The ubiquitous bell curve3m 23s
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Decoding polling results3m 27s
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What is an outlier?3m 15s
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Statistical bias3m 45s
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The importance of regression analysis3m 38s
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Understanding probabilities3m 23s
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Statistics tools3m 19s
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Modern organizations use statistics3m 16s
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Combinations3m 46s
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Measuring variation3m 55s
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Sample space3m 51s
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Election win probabilities3m 41s
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Cognitive bias4m
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Forecasting3m 13s
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Toilet paper4m 5s
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Winning streaks3m 6s
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Coffee3m 6s
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Vaccines2m 44s
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Superfans2m 50s
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US Presidents2m 51s
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The cost of owning a pet2m 45s
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Funny movies3m 23s
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Success in the music industry2m 23s
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Home Improvement3m 4s
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Youth sports3m 30s
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Mental health2m 43s
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Chocolate2m
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Baby statistics2m 30s
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Books2m 48s
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Commutes2m 43s
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Farms2m 15s
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Hip hop2m 50s
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Mass transit2m 43s
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Major league baseball3m 19s
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Placebos2m 54s
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Podcasts2m 13s
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Social media2m 44s
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Supply chains2m 51s
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