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05-30-2008, 04:56 PM
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Statisitcs HELP! Again... I know...
I have another question on the flashcards - I've attached the document, but in a nutshell, the question is - are there more than one SD formula?
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CLEP Hound Retired IT Manager, Working again... It's my dime, so testing all I can. Pursuing Park University MIS degree CLEP - Principles of Mgmt  ; Freshman Comp (68)DSST - Organizational Behavior (61); Principles of Supervision (66); Principles of Finance (71); Statistics (IP)     
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05-30-2008, 05:18 PM
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You divide by N for a population standard deviation, and by N-1 for a sample standard deviation. Take a look here for further explanation. I don't remember this being a cause of confusion when I took the ECE -- seems like knowing that the SD was the square root of the variance was enough for most questions, but don't trust my memory.
 -Gary-
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05-30-2008, 06:08 PM
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Quote:
I see where you got confused because I got stuck at the exact same place!! (I even posted about it!) You only do the n-1 when your SD is for a sample (as opposed to a population). Does your calculator do this for you? Mine does, I just have to enter the data set, and then select which key I want depending on if I want it to calculate SD of a sample or SD of a population. Check your calculator, it can make your life easy. I worked out like 40 of these long hand before I found my magic button 
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Jennifer ALM, Psychology, Harvard University, in progress AA & BA, Social Sciences, Thomas Edison State College, 2008 AOS, Culinary Arts, Culinary Institute of America, 1990 IC WORKS! http://www.degreeforum.net/general-e...g-members.html "Brick walls are there for a reason. The brick walls are not there to keep us out. The brick walls are there to give us a chance to show how badly we want something. Because the brick walls are there to stop the people who don’t want it badly enough. They’re there to stop the other people.” Randy Pausch
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