Question

can anyone explain z-scores please??

Answer 1

http://en.wikipedia.org/wiki/Standard_score

Answer 2

normalized values for a data set

Answer 3

you can make a nice bell curve out of a data set

Answer 4

The z-score basically tells you how many std deviations you are from the mean

z = x-mean/stdev

Answer 5

mhm i get that much. its the algebraic part - the steps that i have trouble with. the entire thing equals one, yes?

Answer 6

yes the area under the entire bell curve is 1.

the area under the curve from z-scores -1 to 1 is about 0.68
the area under the curve from z-scores -2 to 2 is about 0.95
the area under the curve from z-scores -3 to 3 is about 0.99

Answer 7

Example:
say you have a bunch of data with mean = 10, std deviation = 2

z =(x-10)/2
say x = 6 and 14
z = (6-10)/2 = -2 , z = (14-10)/2 = 2

The probability of finding a data point between 6 and 14 is 95%

Answer 8

ohh ok. thanks! that makes sense :) math is not a strong suit....
the example helps too