# The Reality Check #189: Little Genius + Truth Serum + 420

Darren talks about a recent news story about a genius 4 year old, what does her IQ actually mean? Jon examines the truth and fiction surrounding truth serum, can it actually get people to spill the truth? Adam runs a game of science fact or science fiction about the origins of “420”.

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Show Notes

High IQ Children

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### 1 Response to The Reality Check #189: Little Genius + Truth Serum + 420

1. Chris H says:

SOMEONE IS WRONG ON THE INTERNET!!!!

ADAM: “What are these numbers you’re saying… “0.7”?
DARREN: Sorry, correlation 0.7. So that means that one variable explains sort of 70% of the variance of the other one.”

Incorrect, I’m afraid. If you are citing Pearson (or any other) correlation coefficients then the 0.7 refers to a statistical measure of the strength of the correlation, but not the amount of variation explained. The “coefficient of determination” (or “r^2”, where “r” is the Pearson product moment correlation coefficient) gives an estimate of the proportion of variance explained in the dependent variable by the independent variable in a simple linear regression. In this case, a Pearson correlation coefficient (“r”) of 0.7 gives a coefficient of determination (“r^2”) of 0.49, so 49% of the variance is explained.