Mean or median? Replace some of 15 commute distances with wrong values
how many of the 15 values are wrong (the largest are replaced)
the wrong value
mean
median
wrong value
Why divide by n − 1? Thousands of samples from a population whose variance is 1
sample size n
draw 20,000 new samples
divide by n
divide by n − 1
true variance 1
What r does and does not see: click to add a point, drag to move it
remove last point
Correlation and causation, in both directions
effect of the advert on liking, group A (per hour seen)
effect of the advert on liking, group B
remove the effect of town population from both (plot what is left)