Normal Curve: What is it and why is it important?
* a really solid description of this information can be found here: https://www.mathsisfun.com/data/standard-normal-distribution.html
68 - 95 - 99.7 rule
* height of people in the room here
z-scores (also called normal scores). This puts everything on a level playing field, and allows us to compare sets of normal data with VASTLY different means and standard deviations.
finding a z-score:
http://www.r-tutor.com/elementary-statistics/probability-distributions/normal-distribution
* SAT = N(500, 100)
* ACT = N(18, 6)
using z-scores, we can compare SAT and ACT scores.
finding a p-score
two ways:
1) use a table. We need to know whether we are talking above the value, below the value, or inside a range of values. draw a picture; it puts things in perspective.
2) use r. the following command: pnorm(yourvalue, mean, sd)
note: this always gives the lower tail, so still draw a pic...
there's also a way to go backwards on this ... qnorm(your'p'value, mean, sd)