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Rali

Re: 95% Conf. Int

in spss you just go in descriptive statistics and then go right side button statistics there u will definitely find the confidence int ok

rqayyum

Re: Re: Re: Re: Re: Re: 95% Conf. Int

I don't use SPSS so cant help there, perhaps someone else may know. While there are several methods for calculating 95%CI of a proportion (Exact, Wald, Wilson, Agresti, Jefferys) they all give about the same values.

The easiest method (and you can do it by hand) is as below:
1. calculate standard error by using
sqrt(p(1-p)/n)
2. Multiply this standard error with 1.96 (z-value for 95%CI)
3. Add (or subtract) the resulting number to your proportion; this will give you upper (or lower) limit of 95%CI

Here p is proportion which in your case is 0.25; n is your sample size.

Please note, as I have stated earlier, methods for calculating 95%CI vary depending upon your data and research question and the above method will not work in most other cases; however, it will work for calculating 95%CI of any one proportion.


[Edited by rqayyum on 13-07-2010 at 05:47 PM GMT]

tariqasl

Re: Re: Re: Re: Re: 95% Conf. Int

I am very thankful to you, but what is the method to calculate and how to calculate these in SPSS?
Thanks for help

ibrahim_ap

Re: Re: Re: Re: 95% Conf. Int

for your results below is 95% CI for 25%
Exact 90% C.I. (Mid-P) = 0.202 to 0.303
Exact 90% C.I. (Fisher's) = 0.200 to 0.305
Exact 95% C.I. (Mid-P) = 0.194 to 0.314
Exact 95% C.I. (Fisher's) = 0.192 to 0.316
Exact 99% C.I. (Mid-P) = 0.177 to 0.334
Exact 99% C.I. (Fisher's) = 0.175 to 0.337

For any details feel free to call 0300-4668681

tariqasl

Re: Re: Re: 95% Conf. Int

I have 200 sample size; the prevalence of X problem is in 50 patients i.e. 25%. Now the reviwer says that dont mentions the 25% only, but also mention the 95%CI values as well.
Now how to calculate it?
I have given example of X, But i have to calculate prevalence of many other problems.......
Plz help---
Thanks