here is the number given 12, 16, 10, 9, 18, 5, 14, 11, 20
i know how to find the population variance but i can't figure out the dam sample variance
i got 12.8 as a mean and the n=8 since 9-1=8
how do i get the variance?
plz help
i know how to find the population variance but i can't figure out the dam sample variance
i got 12.8 as a mean and the n=8 since 9-1=8
how do i get the variance?
plz help
-
Do it the same way as the population variance, except divide by (n-1) instead of n.
-
This is from wiki, it gives an example.
value of (1 + 2 + 3 + 4 + 5 + 6) / 6 = 3.5. Its expected absolute deviation — the mean of the equally likely absolute deviations from the mean (3.5 − 1, 3.5 − 2, 3.5 − 3, 4 − 3.5, 5 − 3.5, 6 − 3.5) — is (2.5 + 1.5 + 0.5 + 0.5 + 1.5 + 2.5) / 6 = 1.5. But its expected squared deviation —its variance (the mean of the equally likely squared deviations) — is (2.52 + 1.52 + 0.52 + 0.52 + 1.52 + 2.52) / 6 = 17.5/6 ≈ 2.9.
value of (1 + 2 + 3 + 4 + 5 + 6) / 6 = 3.5. Its expected absolute deviation — the mean of the equally likely absolute deviations from the mean (3.5 − 1, 3.5 − 2, 3.5 − 3, 4 − 3.5, 5 − 3.5, 6 − 3.5) — is (2.5 + 1.5 + 0.5 + 0.5 + 1.5 + 2.5) / 6 = 1.5. But its expected squared deviation —its variance (the mean of the equally likely squared deviations) — is (2.52 + 1.52 + 0.52 + 0.52 + 1.52 + 2.52) / 6 = 17.5/6 ≈ 2.9.