I know this is a funny question, because almost no one has enough information to have a realistic estimate. It is a lot like asking  "how many angels can sit on the head of a pin", or "what color are God's eyes?"

In three or four days, the form had collected more than 1,800 responses, ranging from - 95 to many billions.

Many of the guesses were joke answers, such as "infinity over zero", "500 humans and 63 pets", and "Two. They're both ex-girlfriends" which is what I've learned to expect from the internet citizenry. Bless them! In fact, given the impossibility of providing a well-informed answer, you could almost consider all of these answers joke answers.

A few people did not answer the question, acknowledging that it was absurd: "How should anyone know who or how many people may be here and planning to cause some malevolence. I don't know that I have any right to even suppose what number of people (there are)", "How would we even know?" and "Are you serious? There is absolutely no way of estimating this"

I attempted to organize the data. 

The astronomical numbers at the high end of the scale (9e+2871) made the mean average very high, (more than a billion googol).

• The median average was 150.
• 46 responses were zero.
• 16 responses were "too many".
• 35 responses were larger than 230 million.
• Many responded that they did not like terrorists.
• About a dozen responded with the names of political figures.
• The most popular answer was 100.

I made a chart. When I split the 1,842 responses into six even groups, there were 307 responses in each group.

The first group, which you might call the "there aren't many terrorists" segment, guessed a number between -95 and seven.
The second group responded that there are from 8 to 42 terrorists.
The third higher group all gave numbers between 43 and 150.
The fourth group answered between 151 and 999.
The fifth group of 307 responded between 1,000 and 5,000
The highest segment of answers responded with numbers above 5,000.

The chart to the right shows these six even segments.

If you would like to read the (almost) raw responses, I should warn you that there are a lot of them. They are spread onto three pages: 1 2 3.

If you want to paste these into Excel and analyze them yourself, the results in numerical order are here: webpage | text. Let me know if you find the Kurtosis.

I plan to have another terror quiz in a couple of weeks. This second quiz will get into the guts of terrorism. I'd appreciate it if you would come back and respond. Thank you!

-Rob