CatPhish Posted February 21, 2004 Report Share Posted February 21, 2004 I'm struggling through a distance ed. Statistics Course and my school disscussion board is down for construction at the moment. Math is a sore spot for me and I just need this friggin course to move on. Just wondering if anyone here could varify if I am undersatnding the calculation for Standard Deviation (score subtracted from the mean)2 __________________________________ # of samples-1 Not the best Saturday morning post ever I know Link to comment Share on other sites More sharing options...
rubberdinghy Posted February 22, 2004 Report Share Posted February 22, 2004 2+2=4 2x2=4 Link to comment Share on other sites More sharing options...
Big Wooly Mammoth Posted February 22, 2004 Report Share Posted February 22, 2004 you're almost there. variance = sum(score subtracted from the mean)2 / (N-1) the standard deviation is the square root of the variance you were missing the summation part. i.e. you want to add up all of the (score subtracted from the mean) data points and then divide that by (N-1). then take the square root of that. Link to comment Share on other sites More sharing options...
rabidmonkey Posted February 22, 2004 Report Share Posted February 22, 2004 That's pretty much it. Standard deviation is the square root of the variance. The variance is calculated by this formula: (the sumation of X^2) - [(the sumation of X)^2 / n ] ________________________________________________ # of samples - 1 I'm taking a Stats course right now so I think this is right, however I'm not known to remember things. Link to comment Share on other sites More sharing options...
CatPhish Posted February 22, 2004 Author Report Share Posted February 22, 2004 Thank you so much guys. That missing step makes all the difference. I need a beer! Link to comment Share on other sites More sharing options...
secondtube Posted February 22, 2004 Report Share Posted February 22, 2004 anymore help, just ask. i finished my college stats course last semester, and grabbed an A- It was actually the easiest math that i took in college. (for me). The hardest for me was the Math of Finance... Had to take it twice. Link to comment Share on other sites More sharing options...
CatPhish Posted February 22, 2004 Author Report Share Posted February 22, 2004 Ok so how about Z scores. This is what I understand but not sure if it's right. for example finding the Z score for someones's income would be the income - the mean income ____________________________ the standard deviation Link to comment Share on other sites More sharing options...
rabidmonkey Posted February 22, 2004 Report Share Posted February 22, 2004 That is correct. Link to comment Share on other sites More sharing options...
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