The age difference between the partners is depicted two ways. First, the age differences were segmented into three year groups, 3 years or less, 4-6 years, and so on. The number and percentage for each group is shown in the table below.
| Frequency | Percent | Cumulative Percent | ||
|---|---|---|---|---|
|
Age Difference (in years) |
<=3 | 17 | 9.0 | 9.0 |
| 4-6 | 21 | 11.1 | 20.1 | |
| 7-9 | 25 | 13.2 | 33.3 | |
| 10-12 | 22 | 11.6 | 45.0 | |
| 13-15 | 36 | 19.0 | 64.0 | |
| 16-18 | 22 | 11.6 | 75.7 | |
| 19-21 | 18 | 9.5 | 85.2 | |
| 22-24 | 7 | 3.7 | 88.9 | |
| 25-27 | 10 | 5.3 | 94.2 | |
| >=28 | 11 | 5.8 | 100.0 | |
| Total | 189 | 100.0 | ||
The age difference is represented graphically in the histogram below. Each column represents one year. The mean age difference for all couples is 13.7 years.
Comparing the actual distribution with the normal curve suggests that smaller age differences predominate. If the seven outliers are removed from the data--those with an age difference >30 years, because outliers have a disproportionately strong influence on the mean--the mean is reduced by almost a full year from 13.7 to 12.9 years, the median from 14 to 13 years, but the mode 14 year difference is unchanged.