Needed: A large database of statements for true/false exercises

Download a bunch of historical stock price information, then ask questions like "Did company X's stock go up the day after event Y?" (Did IBM go up after the Berlin Wall fell?)

You could use data about countries (this site looks like it has a number of links to spreadsheets) and randomly generate questions of the form "Does [country] or [country] have higher [economic statistic]?". If it's a concern that the questions would be too easy, you could pick only cases where the statistics are in fact reasonably close.

statements that are ~50% true... this is actually pretty hard, mine some dataset for statistical info?

generally, I would look into RDF, (protege and topbraid composer free will let you poke around for free without knowing the data format)

US 2000 Census in RDF

Freebase has all manner of data in RDF

http://aws.amazon.com/publicdatasets/ public data sets, not all in RDF but "it's more important that the data have structure" and all that

cancer stats

You could take a look at the 15 million statements in the database of the Never-Ending Language Learning project. The subset of beliefs for which human-supplied feedback exists and beliefs that have high-confidence truth values may be appropriate for your purpose.

roughly 50% likely to be true or false

I feel like you'd need to specify for what kind of person these statements shall appear about 50% likely. That can be very different across different knowledge backgrounds. I, as a European, have no idea whether or not Iowa and Ohio are neighboring states.

That said, I think geographical questions might do well because such statements should be easy to generate and find evidence for/against.

Examples:

• The Great Slave Lake is the 11th largest lake in the world
• Algeria is the 12th largest country in the world
• Israel is bigger than New Jersey
• Germany is smaller than Montana
• Sulawesi is one of the ten largest islands in the world

(some of these are false, some are true).

To create these statements, one could look up wikipedia lists, e.g.List of islands by area, List of countries by area, List of rivers by length and so on.

Writing a script that extracts statements from this type of data should be feasible, and one could write it such that for each true statement extracted, a wrong statement is created as well.

I find it very hard to judge these questions, however given a world map (without borders) this changes. Also, you could tell me how many people live in the countries/states mentioned, how large one of this countries is in absolute numbers or what the greatest depth of the Great Slave Lake and fifteen other lakes in the world is.

Once these statements are available, they could not only be used for calibration training, but also for exercises about seeking the truth in groups.

It might be possible to have subject matter experts assemble sets of such questions about their areas. We have a lot of people with different expertise on LW and so it wouldn't be that hard. For example, I could pretty easily supply 5-10 such questions in a math context or in a history of science context.

You could try using PredictionBook? I don't really know what your specific needs are so I don't know if PB could really be adapted for your needs.

Going for a trivia database seems like your best bet. I just had a look at www.triviadatabase.com (first google result for "trivia database") and the questions seem relatively neutral in terms of intuitiveness.

"What is the addictive chemical in cigarettes?" "What unit is force measured in?" "What country did King Hussein rule?"

Keep in mind that it's much harder to generate tricky questions than simple ones, so it's unlikely you'll have much cleverness in a big database unless it's extremely expensive.