finding the estimated mean, median and mode for grouped data in data mining
How to calculate the estimated mean and estimated median of grouped data?
In this tutorial, we will try to learn the followings;
- Estimated mean
- Estimated median
- Estimated mode
- Class intervals
| Age | Mid of age | Frequency | Mid * Frequency |
| 21 – 25 | 23 | 5 | 23 * 5 = 115 |
| 26 – 30 | 28 | 2 | 28 * 2 = 56 |
| 31 – 35 | 33 | 6 | 33 * 6 = 198 |
| 35 – 40 | 37 | 8 | 37 * 8 = 296 |
| Total | 21 | 665 |
Estimated Mean = 665 / 21
= 31.66
Class intervals:
Group 21 to 25, 26 to 30, 31 to 35 and 35 to 40 are class intervals.
Mean is 31.6 so 31.6 rounds to 32.
Estimated mean = 32
Median group = 31 to 35
Estimated Median = ?
Estimated Median = L + (TV / 2) – SBM ⁄ FMG * GW
| L = Lower boundary of median group | 30.5 |
| TV = Total number of values | 21 |
| SBM = Sum of frequencies before median group | 7 |
| FMG = Frequency of median group | 6 |
| GW = Group width | 5 |
Result: Our median group is 31 to 35 and yes estimated median 33.4 is in the median group.
How to calculate the estimated mode of the above-grouped data?
| L = Lower boundary of the median group | 30.5 |
| SBM = sum of frequencies before the median group | 7 |
| FMG = Frequency of median group | 6 |
| FBMG = Sum of frequencies of all groups before the median group | 7 |
| FBMG = Sum of frequencies of all groups after median group | 8 |
| GW = Group width | 5 |
Mode: Mode is the most occurring Value in the data.
Video Lecture
Next Tutorials with Similar Topics
- Type of Data that can be mined – Click Here
- Attributes Types – Click Here
- Mean, Median, Mode – Click Here
- Estimated Mean, Median, Mode –