Classifying Data
Frequency Distribution, Variance, and Standard Deviation
The frequency distribution is the tabular grouping of data into different classes or categories. In a frequency distribution, the variance and the standard deviation can be computed manually. The variance is the average of squared deviation from the mean, while the standard deviation is the square root of the variance.
Frequency Distribution of Rice Plant to Plant Height
| Rice Plant Numbers | Plant Height ( x) | Deviation from the Mean ( x-x ) | Squared Deviation from the Mean (x-x )² |
|---|---|---|---|
| 1 | 8.5 | -1.3 | 1.69 |
| 2 | 10.0 | 0.2 | 0.04 |
| 3 | 9.0 | -0.8 | 0.64 |
| 4 | 8.5 | -1.3 | 1.69 |
| 5 | 8.0 | -1.8 | 3.24 |
| 6 | 15.0 | 5.2 | 27.04 |
| Total | 59.0 | 0.0 | |
| Mean | 9.8 | 0.0 | Total: 34.34 (variance) 5.86 (standard deviation) |
Variance can be described as the sum total of squared deviation from the mean while the standard deviation is the square root of the variance. You can find the mean, variance, and standard deviation using a scientific calculator. Both measures of dispersion can inform you how close and how spread the individual values are to one another.
