z score (2 Viewers)

[SKA]

hey can some1 tell me the formula for z score

i forgot to write it down n cant remember now

cheers.

 

[Grey Council]

z score? Whats that? sorry, can you please explain? ta

 

[SKA]

something to do with standard deviations... umm umm i dunno how to explain it... something to do with how many standard deviations above or below a mean???

so if the mean is 50 and some1 scored 55 and the standard deviation is 1.. then the z score for that person woulld be +5

but there is a formula
something like
the something+the something divided by the mean?

 

[Grey Council]

no idea. lol, i've forgotten all statistics. did it last year. sorry

 

[hipsta_jess]

hmm...looks for formulae sheet...cant find one...looks on the web..

z=x-mean
______
standard deviation

a formulae sheet can be found http://www.boardofstudies.nsw.edu.au/syllabus_hsc/pdf_doc/maths_gen_formulae.pdf

 

[Cape]

z score is referring to normal distribution. I.e:

* Approximately 68% of all the scores fall within 1 standard deviation of the mean. This means that 68% of the scores have a z score between 1 and -1.

* Approximately 95% of the scores lie within 2 standard deviations of the mean. In other words, 95% of the scores have a z score between 2 and -2.

* Approximately 99.7% of the scores lie within 3 standard deviations of the mean. That is, they have a z score between -3 and 3. This infers that scores will almost certainly lie within 3 standard deviations of the mean.

z = x - mean / s
Where z = z score
x = score
s = standard deviation.

 

[SKA]

fanks jess n cape

 

[bubz :D]

ok let me see if i can remember this LOL
i think it's z = x - mean / s

(the mean is usually represented by an x with a line above it)

edit oh ok whoops i didn't see the formula at the end of cape's post

 

[SKA]

jejeje.. thanks for ur help ne ways bubz

 

[Cape]

Originally posted by SKA
fanks jess n cape

Its k, no probs

 

[Misturi]

l just use my calculator...

 

[SKA]

jejeje.. yeh i do too now.....

we just had a test n it was in it.. i got that bit all right thats all i know so far... gotta wait till tests come back