Why is the standard deviation in the minitabs different from the answers that are mostly given in text books?
2007-02-11 05:02:06 · 3 answers · asked by bhoots5 2 in Science & Mathematics ➔ Mathematics
Some measures of standard deviation use a divisor of n-1 and others use n
i.e std dev^2 =1 / (n-1) x Sum ( ( x(i) - xaverage ) ^2)
or std dev^2 =1 / n x Sum ( ( x(i) - xaverage ) ^2)
The former is used for the standard deviation of a sample - it is considered an unbiased estimate of the sample standard deviation.
The latter is the standard deviation of a population (i.e. the full dataset).
2007-02-11 08:34:15 · answer #1 · answered by zac o 1 · 2⤊ 0⤋
Depend son how you work it out: if you use the population (n), or the standard population (n-1).
The latter is for a fixed small population and complete data set, the former is for a sample of a large population, you have to make a decision which it is.
Text books can be wrong, so can Minitab, but not usually. If everyone else is wrong, then you have to at least question your own methods
2007-02-11 08:37:29 · answer #2 · answered by BadWolph 3 · 0⤊ 0⤋
the text books are wrong. we used to do it last year when i was doing additional maths. well at least i think they where lmao x
2007-02-11 05:11:47 · answer #3 · answered by chris c 3 · 0⤊ 0⤋