1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Degrees of confidence

  1. Sep 6, 2010 #1
    Hi, I'ld like to know if anyone knows how to find the 'z' score inrelation to a percentage degree of confidence. The question is: Determine the z score that would give a result with a degree of confidence of 95%.

    I know that it is, 1.9600. However, I would like to know how to figure this out mathematically.

    Thanks,
    Sirsh.
     
  2. jcsd
  3. Sep 7, 2010 #2
    It's based on the area under the standard normal distribution:
    [tex]\frac{1}{\sqrt{2\pi}} e^{-\frac{1}{2}z^2} [/tex]

    Your question "Determine the z score that would give a result with a degree of confidence of 95%." comes down to "what is the value of z such that the area under the standard normal distribution between -z and z is equal to 0.95?". And it turns out that:

    [tex]\int_{-1.96}^{1.96} \frac{1}{\sqrt{2\pi}} e^{-\frac{1}{2}z^2} dz \approx 0.95[/tex]
     
  4. Sep 11, 2010 #3
    Thanks alot, gerben!
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook




Loading...
Similar Threads for Degrees confidence Date
Cosine of 330 degrees Mar 30, 2018
Find the value of beta in degrees Jan 26, 2018
5 degree equation contains imaginary value? Jun 20, 2017
Finding sample size given info on confidence interval Jun 28, 2014