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mariomintchev
Can someone explain the STANDARD DEVIATION OF THE DIFFERENCES formula to me?
@jagatuba @Jemurray3 @jhonyy9 @karatechopper @phi @robtobey @satellite73
I am given 2 sets of 10 numbers. How do I plug them into this formula to get the correct answer?
so what numbers you have got for ????
the sum across the values how you can get it ?
im confused about the top part of the formula. ive been getting the wrong answers so i must be doing something wrong.
sorry but this attachement i not can opening ,not id compatibly with my excell programm
can you rewrite me here the values for x and X the mean or average and the value for n ?
@robtobey can you opening this attachement please ?
(column 1) x = 129, 237, 110, 32, 322, 134, 119, 32, 172, 149 total sum for x = 1436 mean for x = 143.6 (column 2) y = 130, 224, 113, 38, 320, 124, 122, 33, 169, 148 total sum for y = 1421 mean for y = 142.1 value for n = 10 df = n-1 (so 9)
have you any idea for this ?
yes but ive been getting the wrong answers. d bar = 1.5 so ive been doing ((129-1.5)^2+(237-1.5)^2+(110-1.5)^2+.......))
so how i see it there will be in numerator sqrt(sum(x-X)^2) divide by sqrt9 so divide by 3 ok ?
can you calcule first this sum ?
how many will be this sum ?
i got 270258.5 for x and 261262.5 for y then i subtracted the 2 to get 8996
then divide by 9 and square root it to get 31.616
why divide by 9 and not by 3 ?
arent u supposed to do whats in the radical first and then square root it?
why you can separte it sqrt of numerator and sqrt of denominator and vide it after
i get the same answer either way
the right answer is 5.93
@jhonyy9 It may to late for solving this problem. Attached is a screen capture of part of the xls file. I am running on a mid 2010 IMac with 8Gb of ram to support virtual versions of Windows XP pro, Windows 98SE and in the past Ubuntu Linux. The xls file is not a normal spread sheet data file. All I can provide is a screen capture of what I see.
how can i opening it what program i need using for ?
i provided all the necessary info above ^^^^^
so than you need calcule right this sum and after make the squareroot of them ,yes ?
so and after just divide it by 3
Ask @mariomintchev what version of Excel did she/he use to generate the spread sheet.
They want the standard deviation of the differences. Your formula tells you how to find the standard deviation of a list of numbers. The first step is find the list of numbers: the list of differences so find x-y where x= 129, 237, 110, 32, 322, 134, 119, 32, 172, 149 y = 130, 224, 113, 38, 320, 124, 122, 33, 169, 148 the differences (call it z) are z= -1 13 -3 -6 2 10 -3 -1 3 1 now use your formula to find the standard deviation
so ((-1-1.5)^2+(13-1.5)^2+(-3-1.5)^2+....)) ???
yes, then divide by 9 then take the square root.
ok, i got 5.95 so its close enough. thanks phi, i can always rely on you!
I got 5.930 (dd-1.5).^2 6.2500 132.2500 20.2500 56.2500 0.2500 72.2500 20.2500 6.2500 2.2500 0.2500 sum(ans)/9 = 35.1667 sqrt(35.1667)= 5.9302
i must have made a little mistake somewhere when punching in all of those numbers and parenthesis. i understand what i need to do now though. thanks! =o)