curves and sampling distributions
chapter 6 lessons 1 and 2
EMPERICAL RULE (6.1)
For a distribution that is symmetrical and bell-shaped:
- 68% of the data values will lie within 1 standard deviation on each side of the mean
- 95% of the data values will lie within 2 standard deviations on each side of the mean
- 99.7% of the data values will lie within 3 standard deviations on each side of the mean
Z SCORES (6.2)
- the z value or z score (aka standard score) gives the number of standard deviations between the original meausrement x and the mean u of the x distribution