Prenatal Test False Positives: Bayes’ rule is still very, very important

Posted here are a NYT Article about genetic testing companies and the value of the results they provide along with an additional explanation of the math behind the issues.

Altogether, there are 415 positive tests: the 15 true positives, and 400 false positives. So if you get a positive test result, the chance that the fetus is actually affected is about 3.6%.

On its face, this sounds like a really good test! It detects 75% of cases, with only a 0.5% false positive rate. That seems like it should be helpful.

Further discussion from this author about Bayes’ rule

Numbers don’t lie…or can they? Interesting case of Illinois’s tax increase

In 2011, the state of Illinois increased its state income tax rate from 3% to 5%. One could communicate this by saying that people will be paying 2% more of their incomes to state taxes which doesn’t sound all that bad since Illinois increased its rate rate 2%. Or you could say that Illinois increased its state income tax by 66% which sounds catastrophic and is also correct because you’re changing what the number actually is referring to. Increasing from 3 to 5 is an increase of 66% (or 66.6% to be more accurate with a bar over the last 6 but I don’t know how to do that on a keyboard). People would react to the news differently depending on how you communicate even though both could be considered correct.

Here are two different sites reporting the story. Notice how the choice of language and numbers changes the feel of each story even though they are both reporting the same news.

Different Bible Translations

Here is a link to a great website that compiles a bunch of different Bible translations. What’s fascinating is to compare the same verse from the different translations and interpretations to see varied the texts can be. How important is language when it comes to communicating ideas particularly with something as important as religion?

Here is a link to a famous passage from the Bible, John 3:16

Depending on which translation you chose to read, you would come away with very different ideas about what God expects of people.

Here’s a link to the main site.

All of this raises interesting questions about what the job of translators and interpreters is. Are they supposed to translate literal words? Are they supposed to communicate meaning even if some words have to change? How are you supposed to know the choices they made are accurate or true?

Here is a handout I made on this topic

Compare and Contrast John 3 16

RSA Animate – Language as a Window into Human Nature

Why do we indirect language and innuendo?
What does the language we use tell us about our social relationships?
How does the language we use reflect ideas of personal and shared knowledge?

In this new RSA Animate, renowned experimental psychologist Steven Pinker shows us how the mind turns the finite building blocks of language into infinite meanings.

Quiz: Can you read people’s emotions?

“If you are among those people who are mystified by moods, new research offers hope. A new study shows that certain types of reading can actually help us improve our sensitivity IQ. To find out how well you read the emotions of others, take the Well quiz, which is based on an assessment tool developed by University of Cambridge professor Simon Baron-Cohen.”

Here is a handout I made based on the quiz

can you read people_s emotions

Click below for the full quiz

What do the newly released witness statements tell us about the Michael Brown shooting?

table-finalfinalup4“Over the course of the investigation, federal agents interviewed dozens of witnesses—some compelled to come forward by subpoena—to piece together what happened on that August 9 afternoon. Shortly after the press conference announcing the jury’s decision, St. Louis County Prosecuting Attorney Robert McCulloch released the transcripts of interviews with witnesses and Wilson.

We read and analyzed more than 500 pages of witness testimony and compared each statement to those given by Wilson. Below is a chart comparing several key details of the officer’s report to the witness statements. Was Brown facing Wilson when he was shot, or was his back turned to him? Did Brown have his hands in the air, or were they reaching toward his waist?”