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

[statshelp]

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

Please Help!

 

[royhaas]

Re: confidence interval question

How do you calculate the length of a confidence interval?

 

[statshelp]

Re: confidence interval question

Max confidence interval - Min confidence interval / 2

 

[royhaas]

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]

Re: confidence interval question

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

 

[royhaas]

Re: confidence interval question

Just like the calculation implies.

 

[statshelp]

Thanks, it just seemed to easy.