Degrees of freedom and Standard deviation - AnalyticBridge 2019-08-17T13:01:06Z https://www.analyticbridge.datasciencecentral.com/forum/topics/degrees-of-freedom-and?commentId=2004291%3AComment%3A339556&x=1&feed=yes&xn_auth=no Imagine i ask u to choose 5 n… tag:www.analyticbridge.datasciencecentral.com,2016-01-23:2004291:Comment:339556 2016-01-23T18:43:54.031Z R.Venkat https://www.analyticbridge.datasciencecentral.com/profile/RVenkat <p>Imagine i ask u to choose 5 numbers that sum up to 100.</p> <p>For simplicity sake u tell me the 5 no.s are 20, 20, 20, 20, 20.</p> <p>But when you utter 20 fourth time, i tell you to stop and ask you what was our goal</p> <p>you tell me that the goal was to choose 5n.o s that sum up to 100. So at this point i ask you how much total we have. you reply we have 80. So to get to 100, i ask how much more we need.</p> <p>You tell me that is simple 100 -80 = 20, i.e another 20.</p> <p>So here in…</p> <p>Imagine i ask u to choose 5 numbers that sum up to 100.</p> <p>For simplicity sake u tell me the 5 no.s are 20, 20, 20, 20, 20.</p> <p>But when you utter 20 fourth time, i tell you to stop and ask you what was our goal</p> <p>you tell me that the goal was to choose 5n.o s that sum up to 100. So at this point i ask you how much total we have. you reply we have 80. So to get to 100, i ask how much more we need.</p> <p>You tell me that is simple 100 -80 = 20, i.e another 20.</p> <p>So here in this case u had degree of freedom to choose only 4 numbers i.e (20,20,20,20). Due to the specified condition of getting 5 no.s summing upto 100, the 5th number chose itself,</p> <p>hence the saying N-1. (5-1 = 4 is your degree of freedom).</p> <p>Hope i could explain your query.</p> <p>Regards</p> <p>Venkat</p> Hi to get an unbiased estimat… tag:www.analyticbridge.datasciencecentral.com,2011-02-17:2004291:Comment:90402 2011-02-17T20:31:59.769Z Tomas Keller (formerly Ohlson) https://www.analyticbridge.datasciencecentral.com/profile/TomasKeller <p>Hi</p> <p>to get an unbiased estimation of the standard deviation you have to divide by n-1. You get an explanation why in <a href="http://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation" target="_blank">http://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation</a></p> <p> </p> <p>Hope this helps,</p> <p> </p> <p>Tomas Keller</p> <p>Hi</p> <p>to get an unbiased estimation of the standard deviation you have to divide by n-1. You get an explanation why in <a href="http://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation" target="_blank">http://en.wikipedia.org/wiki/Unbiased_estimation_of_standard_deviation</a></p> <p> </p> <p>Hope this helps,</p> <p> </p> <p>Tomas Keller</p>