[ View menu ]

Archive for 'R'

Some code to help you remember numbers

Filed in Encyclopedia ,Ideas ,Programs ,R
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

Two posts ago we showed you the digit sound system for remembering numbers. This week we provide two computer programs to help you create mnemonics.

You’ve got the whole world in your portfolio

Filed in Encyclopedia ,R ,Tools
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

A famous finance professor once told us that good diversification meant holding everything in the world. Fine, but in what proportion?

Suppose you could invest in every country in the world. How much would you invest in each? In a market-capitalization weighted index, you’d invest in each country in proportion to the market value of its investments (its “market capitalization”). As seen above, the market-capitalization of the USA is about 30%, which would suggest investing 30% of one’s portfolio in the USA. Similarly, one would put 8% in China, and so on. All this data was pulled from the World Bank, and at the end of this post we’ll show you how we did it.

Keep your files in sync for free

Filed in Ideas ,R ,Tools
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

It is not uncommon to have two computers at work, four at home and a server out on the wild, wild internet (that’s what we have, anyway … wait, we forgot one in London). How to keep all these files in sync? Here are our file synchronization tips.

Do cents follow Benford’s Law?

Filed in Ideas ,R
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

Benford’s law is an amazing thing. If you know the probability distribution that classes of “natural” numbers should have, you can detect where people might be faking data: phony tax returns, bogus scientific studies, etc.

Dollars and cents: How are you at estimating the total bill?

Filed in Ideas ,R
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

When estimating the cost of a bunch of purchases, a useful heuristic is rounding to the nearest dollar. (In fact, on US income tax returns, one is allowed to omit the cents). If prices were uniformly distributed, the following two heuristics would be equally accurate:

* Rounding each item up or down to the nearest dollar and summing
* Rounding each item down, summing, and adding a dollar for every two line items.

How many NYC restaurants get As on their health inspections?

Filed in Gossip ,Ideas ,R
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

Decision Science News is no stranger to misleading infographics in free New York newspapers. We could stop reading them entirely, but we find that playing “spot the infographic flaw” makes time fly on the subway.

Recently we saw the above graphic in a paper called Metro. Can you spot the goof?

On not going viral

Filed in Ideas ,R ,Research News
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

This week the reader is directed to Messy Matters to read up on research conducted by Sharad Goel, Duncan Watts and Dan Goldstein in which they hunted for traces of “viral” diffusion on Twitter, Facebook, Yahoo!, and beyond. The results run counter to mainstream intuition.

Best graph ever

Filed in Gossip ,Ideas ,R ,Tools
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

Best graph ever. LARGEST EVER DIFFERENCE BETWEEN 328 and 327 SPOTTED IN NEW YORK CITY

The housing bubble by city

Filed in Ideas ,R ,Tools
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

The housing bubble by city. Miami sailed high and fell far. Detroit rose modestly and but dropped more than it went up. Dallas held steady. DC is enjoying a bit of renewed growth, but are in and New York yet to fall?

Area plots unmasked

Filed in Ideas ,R ,Tools
Subscribe to Decision Science News by Email (one email per week, easy unsubscribe)

RESULTS OF THE GREAT AREA PLOT QUIZ If you are the type of reader who remembers things from last week, you may remember the great area plot quiz we had running. This week, we are excited to announce that the results are in. The plot above shows answers to the four questions. The correct answers […]