The Gender Pay Gap Information Act sets out what information companies must publish, but it isn't the most understandable document when it comes to interpreting the data. Here's a simplified version to help you understand what you're seeing here (and in the linked reports).
The Mean Gender Pay/Bonus Gap
The mean is what most people would understand as the average value. The average value is the sum of all numbers in a data set divided by the number of numbers. The mean or average is a very common way to get an idea of the mid-point of a dataset, but it can be distorted by unusually high or low individual salaries. e.g. If your dataset looked like this (1000, 40, 10, 20, 40), the mean or average would be 222. This isn't really a good demonstration of the middle point of this dataset, as one large number has distorted the overall result.
( + + + + )/5 (total number of people) = the mean value
The Median Gender Pay/Bonus Gap
The median is another way to find the mid-point of a dataset. Unlike the mean, the numbers are lined up in order, and then the median is the middle point of that list. The median is less likely to be distorted by an unusually large or small value, and so can sometimes be a better representation of the general pay gap in a company. If we use the same dataset as before (1000, 40, 10, 20, 40) lining it up in order would result in (10, 20, 40, 40, 1000). The median in this case is the third number in the list, or 40. This result has not been impacted as strongly by the single large number. This difference is why companies must report both numbers.
( ) = the middle person in the lineup is the median value
Pay Quartiles
Pay quartiles are a way of showing the gender split for different pay levels within a company. Not every role in every company is paid the same, and sometimes the differences in an hourly mean or median rate can be explained by a lack of women in more senior roles, as these roles tend to be the highest paid roles in a company. Viewing the pay quartiles gives an indication of the gender representation at different levels of the organisation - showing if there are more men than women in senior roles, more women than men in junior roles, etc.
The quartiles are calculated by getting the hourly pay for each employee and ordering them from lowest to highest. This list is then divided up into quarters so that we have four groups, representing the lowest paid employees, the lower middle, the upper middle, and the highest paid employees. Companies should then show, for each of these groups, the percentage of male and female employees. (e.g. In Quartile 1, the lowest paid quartile, 45% of employees are male, and 55% of employees are female). While all companies should be including this data in their reports, you'll find some reports on this site that do not show this data. This is usually because the company in question hasn't calculated the quartiles correctly. Each quartile should add up to 100, because you're showing the gender split for each quarter.
Positive and Negative Figures
Companies are instructed to represent their gender pay gap in relation to male earnings. What that means for the figures is that if you see a positive number, e.g. mean gap of 5.8%, this means that men are earning on average 5.8% more than women in this case. If you see a negative figure, e.g. -10%, this represents a gap in favour of women, meaning that women are earning on average 10% more than men in this case.
Bonus & BIK (Benefit in Kind)
Not all companies offer bonuses or BIK (benefit in kind) to employees. BIK represents benefits that cannot be converted into cash but have a cash value, e.g. the use of a company car, company health insurance, etc. Bonuses are a sum of money added to a person's wages or salary, usually related to performance. Where a company does pay bonuses or offer BIK to employees, they must report on what proportion of male and female employees received these benefits.
What Should Be Included
- The difference in mean hourly pay (including separate figures for part-time and contract employees)
- The difference in median hourly pay (including separate figures for part-time and contract employees)
- The difference in mean bonus
- The difference in median bonus
- The percentage of employees who were paid a bonus
- The percentage of employees who were paid BIK (benefit in kind)
- A list of four pay quartiles, and the percentages of employees that fall into each quartile