Jump to content

  • Log in with Facebook Log in with Twitter Log in with Windows Live Log In with Google      Sign In   
  • Create Account

Submit your paper to J Biol Methods today!
- - - - -

Decision error

  • Please log in to reply
1 reply to this topic

#1 kaika87



  • Members
  • Pip
  • 2 posts

Posted 24 November 2009 - 01:05 AM

Hello all,

Sampling size has always been a headache for me. I've read that for most sampling sizes, one can opt to use the following formula

N> [(1.96)(1.96) (0.5)(0.5)] / [(0.05)(0.05)]

And it will give a size of about 384.

But recently I've seen in certain studies which apply the following formula instead.

N> [(1.96)(1.96) (0.5)(0.5)] / [(0.1)(0.1)] which gives a sample size of around 96.

Now I understand that the changes is for decision error as in the range of error which we allow. But why such a change is acceptable in certain studies?

Thanks in advance.

#2 DRT



  • Active Members
  • PipPipPipPipPipPipPipPipPipPip
  • 176 posts

Posted 24 November 2009 - 07:39 PM

The error is the same in both instances (thatís where the 1.96 comes from).
In the first equation the analyst is expecting the difference between the means to be about 0.05 (10% of the size of the standard deviation =0.5), in the second equation the analyst is anticipating the difference between means to be greater (20% of the size of the standard deviation) and thus can use a smaller sample size for the same degree of error.

Home - About - Terms of Service - Privacy - Contact Us

©1999-2013 Protocol Online, All rights reserved.