Posts Tagged ‘statistics’

Do not ask for whom the blog was written…

May 12, 2008

While searching for some other demographic statistics, I was surprised to find:

1. World population reached 3 billion in 1961, and 6 billion in 1999. There were twice as many people in the world of my youth as that of my parents’ youth. (Does that mean my life is worth half as much as theirs, or has demand increased as well? 😛 )

2. In 1900 Africa had 133 million residents and Europe had 408 million residents. Today Africa is larger than Europe with a total population of 810 million to Europe’s 710 million.

3. Every day approximately 365,000 people are born and 152,000 people die. The number of deaths is about the same as the average number of WordPress blogs written per day.

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Bad Weather (Prediction)

April 21, 2008

This morning I finished my last mid-term and I wanted to celebrate, but unfortunately rainy weather limited my options. In order to find out the likelihood of my parade being drenched, I took a look at our online weather report. It said there was a 50% chance of rain.

Then I realized that I had no idea what that statistic meant. Did it mean that there was a 50% chance that it would be raining during any particular instant of the day? Did it mean that 50% of Taipei would get a measurable amount of rain? Did it mean that there was a 50% chance that there will be rain at some point during the day?

The answer is, rat-a-tat-tat, that of previously recorded days with similar weather conditions, 50% of them had a measurable amount of rain at some point during the day.

I looks like I am not the only one confused. I pulled the above definition from a study measuring what people in various cities in Europe and the United States think “x% chance of rain tomorrow” means. The researchers gave people three choices: Time (x% of the time it will be raining), Area (there will be a measurable amount of rain in x% of the applicable area) and Days (x% of previous days with similar weather conditions had a measurable amount of rain sometime during the day). As I mentioned above, the “Days” option is the correct one.

Here is a chart reporting the author’s findings:

rain chart

Go New York!  Interesting how people in Amsterdam were mostly wrong in the same way, while in Athens and Milan the distribution was more even.

Full disclosure: I would have guessed “Time” before I saw the answer.