I wrote about measuring bias yesterday. This comment by Joe Truss (my uncle) adds a lot to the conversation:

To add to the importance of Dave’s comment: a critical aspect of bias is the effect our local environment and context have on our opinions about what is happening in the world at large. People are very poor natural statisticians. When confronted with two similar events we begin to think ‘this is how it is for everyone’. An even deeper ‘local’ event is when we are upset or depressed, the entire world seems to be in line with our feelings. When we feel bad, the world seems bad. 

See: https://www.ted.com/talks/hans_rosling_the_best_stats_you_ve_ever_seen?language=en

https://www.gapminder.org
Take the awareness test on this link. ;-)}

Take the awareness test. I started guessing correctly not because I expected the result I was guessing, but because I was expecting the result to surprise me. We really aren’t good at estimating statistics and we make so much of the very little data we do know… and this shapes our bias… poorly.