| Mean |
$$\bar{x} =
\frac{\sum x_i}{n}$$ |
For values 2, 3, 4, mean = (2+3+4)/3 =
3 |
| Median (Odd) |
Middle value in ordered set |
For values 1, 3, 5, median = 3 |
| Median (Even) |
Average of two middle values |
For values 1, 2, 3, 4, median = (2+3)/2 =
2.5 |
| Mode |
Most frequently occurring value |
For values 1, 2, 2, 3, mode = 2 |
| Standard Deviation
(Population) |
$$\sigma =
\sqrt{\frac{\sum (x_i - \mu)^2}{N}}$$ |
For values 2, 4, 4, 4, 5, 5, 7, σ ≈
1.40 |
| Standard Deviation
(Sample) |
$$s =
\sqrt{\frac{\sum (x_i - \bar{x})^2}{n-1}}$$ |
For sample values 2, 4, 4, 4, 5, 5, 7,
s ≈ 1.51 |
| Range |
Difference between max and min |
For values 1, 2, 3, 4, 5, range = 5 - 1 =
4 |
| Variance
(Population) |
$$\sigma^2 =
\frac{\sum (x_i - \mu)^2}{N}$$ |
For values 2, 4, 4, 4, 5, 5, 7, σ2 ≈ 1.96 |
| Variance (Sample) |
$$s^2 =
\frac{\sum (x_i - \bar{x})^2}{n-1}$$ |
For sample values 2, 4, 4, 4, 5, 5, 7,
s2 ≈ 2.29 |
