coding in S1 Watch

mathsdave
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#1
Report Thread starter 12 years ago
#1
the coding is y = (x-100.5)/100

the value of fy = 748 and fy^2 3943.5 and n=360 and need to find the mean and standard deviation

At what stage is it correct to convert back to x values? At this stage, or after working out the mean and standard deviation using the coded values? really not sure.

thanks
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angelsintuition
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CODING IS DESIGNED TO MAKE WORKING OUT EASIER EG. IF U HAVE MASSIVE VALUES. SD IS THE SPREAD OF DATA SO THAT WILL BE THE SAME EITHER WAY. HOWEVER AS FOR THE MEAN I'M NOT 100% BUT I'M PRETTY SURE THAT IF YOU WORK OUT THE CODED MEAN AND THEN CONVER IT BACK IT SHOULD BE RIGHT. CAN N E 1 ELSE CONFIRM WHTHER THIS IS RIGHT OR NOT MY S1 IS ON WEDNESDAY!
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Aired
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You work out the coded mean and standard deviation, and then convert it into uncoded.

In your question, y = (x-100.5)/100

100y = x - 100.5
x = 100y + 100.5 (With x being the original value, and y the coded value).

The mean of an original value is (100 x mean of coded value) + 100.5

The standard deviation is 100 times the standard deviation of a coded value.
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Vanity
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yep, it's so. in S2 u study why it's like that...
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