[R] Is there any design based two proportions z test?

[John Fox]

Dear Md Kamruzzaman,

To answer your second question first, you could just use the svychisq() 
function. The difference-of-proportion test is equivalent to a chisquare 
test for the 2-by-2 table.

You don't say how you computed the confidence intervals for the two 
separate proportions, but if you have their standard errors (and if not, 
you should be able to infer them from the confidence intervals) you can 
compute the variance of the difference as the sum of the variances 
(squared standard errors), because the two proportions are independent, 
and from that the confidence interval for their difference.

I hope this helps,
John
-- 
John Fox, Professor Emeritus
McMaster University
Hamilton, Ontario, Canada
web: https://www.john-fox.ca/

On 2024-01-16 10:21 p.m., Md. Kamruzzaman wrote:
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> 
> 
> Hello Everyone,
> I was analysing big survey data using survey packages on RStudio. Survey
> package allows survey data analysis with the design effect.The survey
> package included functions for all other statistical analysis except
> two-proportion z tests.
> 
> I was trying to calculate the difference in prevalence of Diabetes and
> Prediabetes between the year 2011 and 2017 (with 95%CI). I was able to
> calculate the weighted prevalence of diabetes and prediabetes in the Year
> 2011 and 2017 and just subtracted the prevalence of 2011 from the
> prevalence of 2017 to get the difference in prevalence. But I could not
> calculate the 95%CI of the difference in prevalence considering the weight
> of the survey data.
> 
> I was also trying to see if this difference in prevalence is statistically
> significant. I could do it using the simple two-proportion z test without
> considering the weight of the sample. But I want to do it considering the
> weight of the sample.
> 
> 
> Example: Prevalence of Diabetes:
>                                                       2011: 11.0 (95%CI
> 10.1-11.9)
>                                                       2017: 10.1 (95%CI
> 9.4-10.9)
>                                                       Diff: 0.9% (95%CI: ??)
>                                                       Proportion Z test P
> Value: ??
> Your cooperation will be highly appreciated.
> 
> Thanks in advance.
> 
> With Regards
> 
> *--------------------------------*
> 
> *Md Kamruzzaman*
> 
> *PhD **Research Fellow (**Medicine**)*
> Discipline of Medicine and Centre of Research Excellence in Translating
> Nutritional Science to Good Health
> Adelaide Medical School | Faculty of Health and Medical Sciences
> The University of Adelaide
> Adelaide SA 5005
> 
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> 
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