Information for pair0101:

Brightness of screen

This is from an experiment that has been performed to generate an example of a cause-effect relation
that is clearly unconfounded.

First column (x): grey value of a pixel that is chosen randomly from a fixed image. The grey value
is displayed by the color of a square on a computer screen

Second column (y): light intensity seen by a photo diode placed several centimeters away from the screen.  

More precisely, the light intensity is measured by the 
Adafruit TSL2591 High Dynamic Range Digital Light Sensor connected to an Arduino microcontroler. 
https://learn.adafruit.com/adafruit-tsl2591/wiring-and-test

The measurement has been performed by D. Janzing in August 2016.

ground truth x->y

