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# Do i use sigma x or Sx?

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1. For A level statistics, when using a graphical calculator to work out the standard deviation there are two results - Sigma x and Sx. I've been told that sx is the sample standard deviation and sigma is population or something like that, however im still confused what exactly that means and i am confused about which i should use depending on the situation in a question. Any help would be much appreciated! Thanks.
2. (Original post by redmcq)
For A level statistics, when using a graphical calculator to work out the standard deviation there are two results - Sigma x and Sx. I've been told that sx is the sample standard deviation and sigma is population or something like that, however im still confused what exactly that means and i am confused about which i should use depending on the situation in a question. Any help would be much appreciated! Thanks.
Sx
3. Well the standard deviation can vary from exam board to exam board so I highly recommend checking out which one they expect. My favourite version is the square root of (Sxx/n-1) which is used by OCR MEI. I wouldn't rely on calculator values whatsoever. If you want, you can check which symbol represents which by just calculating the standard deviation normally, and then comparing by inspection.
4. (Original post by Pi/2)
Well the standard deviation can vary from exam board to exam board so I highly recommend checking out which one they expect. My favourite version is the square root of (Sxx/n-1) which is used by OCR MEI. I wouldn't rely on calculator values whatsoever. If you want, you can check which symbol represents which by just calculating the standard deviation normally, and then comparing by inspection.
Im on AQA, and i unerstand that sx is sample and sigma is population. I dont understand when im supposed to use each one depending on the question.
5. σx is the Root Mean Square Deviation

Sx is the Sample Standard Deviation.... or just Standard Deviation

the mark schemes for S1 usually allow either.

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