confidence int. length known for prop.: how to find margin?

statshelp

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If you know the length of a confidence interval for a proportion, How would you find the margin of error?

Please Help!
 

royhaas

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Re: confidence interval question

How do you calculate the length of a confidence interval?
 

statshelp

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Re: confidence interval question

Max confidence interval - Min confidence interval / 2
 

royhaas

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Re: confidence interval question

No, the length is just the difference between the two endpoints of the interval. Now use the formulas for those endpoints and subtract them.
 

statshelp

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Re: confidence interval question

Ok so once I find the length, I then divide by 2, to find the margin of error?
 

royhaas

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Re: confidence interval question

Just like the calculation implies.
 

statshelp

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Thanks, it just seemed to easy.
 
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