Thursday, November 25, 2010

Equal Pay

This is, once again, a somewhat technical post. It highlights some of the shortcomings of focussing on gender pay gaps as a means of identifying biases in pay. It also raises the question: what is a practically important gap? I do not have a good answer to that question. It would be nice to see some discussion of what makes a pay gap important for practical purposes. A related question is: how much effort should employers put into addressing a pay gap that is in some sense ‘large’ but that has a high probability of being due to chance (i.e. is not statistically significant), bearing in mind that resources that are used for one activity are not available for other activities? Again, there is probably not a unique answer to this question but it would be nice to see it discussed.

The principle of equal pay is equal pay for:

•    Equal work – work that is the same or broadly similar.
•    Equivalent work – work that has been rated as equivalent by a job evaluation scheme.
•    Work of equal value – work that places similar demands on those performing it.

As noted by the Equality and Human Rights Commission (EHRC) the overall gender pay gap is not an indicator of unequal pay. They suggest that it should be seen as an ‘equal opportunity gap’. The analysis in my earlier post suggests that it is not a particularly useful measure of that either. Nevertheless, it is popular.

The tool to check for equal pay is an equal pay audit. Equal pay audits should be carried out for ethnicity and disability as well as gender but gender is often easier since the quality of the data is better. Basically the steps in an equal pay audit are:
1. Determine which people are doing equal work, equivalent work or work of equal value. An organisation that has a job evaluation scheme may assume that everyone with a job evaluated to be in the same grade is doing equivalent work or they may split people on the same grade into groups doing similar work. The latter procedure is preferable if there are enough employees since aggregating over all the employees in a grade could mask problems that were specific to one group.

2. Assess whether men and women are equally paid. There are two situations that might apply: there is systematic bias against women (or men) or a few individual women (or men) are disadvantaged, for example, the way in which starting salary is determined may disadvantage people returning from a career break which tends to disadvantage some, but not all, women. Although carrying out an equal pay audit may uncover instances of the latter it is more usual to concentrate on the former, though both are illegal. The EHRC suggests that the first step is to calculate the average basic pay for men and women and the average total pay for men and women. The EHRC recommends that if the difference between the average pay for men and the average pay for women is greater than 5% or if the difference between the average pay for men and the average pay for women is greater than 3% and there is a pattern of gaps favouring one sex over the other then further investigation is required. 

Most scientists asked to determine whether the difference of two means indicated the presence of systematic bias would probably start by trying a t-test. There are some problems with this approach, especially if the means are calculated from a small number of employees, because t-tests are based on the assumption that the estimate of the mean has a normal distribution. Tests of statistical significance, calculate the probability of observing a difference of at least the size you did observe on the assumption that there is no difference. The larger the value of this probability the more likely it is that the observed effect could have arisen just by chance even if, in fact, there is no difference.  It is not necessary to adopt the convention that a result is significant if the probability of getting a result at least that big is less than 0.05 and not otherwise. Depending on the cost it might be reasonable to take action even if the probability that the observed difference is due to chance is 0.3, or even more, depending on the circumstances. Note that observing an effect that is not statistically significant does not imply that there is no effect. It implies that there is not enough data to say whether or not there is an effect.

As noted by the EHRC, statistical significance should not be confused with effect size  (see Technical Note 3.5). A large difference can fail to be statistically significant if there are a small number of employees, or a small number of employees of one sex. A small difference can be statistically significant if there are a large number of employees. So, for example, an institution might be more worried about a 15% gender pay gap that had a 10% probability of being exceeded due to chance than about a 1% gender pay gap that had a 4% probability of being exceeded due to chance. In the latter case the institution is saying that they are willing to accept a low probability that the observed result is due to chance since they believe the bias to be too small to be of practical importance. What constitutes a large difference? What is practical importance?

The EHRC criteria are that if, on average, one sex earns more than 5% more than the other for doing particular equivalent jobs, or more than 3% more if there is a pattern, then there is a problem that needs investigating. These criteria could lead to anomalies depending on how pay is determined. Organizations that rely on negotiation by individuals to set pay or on pay schemes with a significant component dependent on performance evaluation are open to inadvertent discrimination leading to systematic discrepancies that would be evident in gender pay gaps. Other organizations use a system in which the person identifying the need for a position writes a job specification that is used by a professional job evaluator to assign a grade to the job with the person appointed to the position being assigned to a point within the grade on the basis of their qualifications and experience and then progressing by automatic annual increments to a point at which he or she needs to apply for promotion to discretionary or contribution points of the grade. Under this system there is much less scope for discrimination. Possible ways in which bias can occur are:
1.    There could be a tendency for women to be appointed at a lower point in the grade.
2.    Women could be less likely to apply for promotion to discretionary or contribution points.
3.    The job evaluation scheme could result in jobs predominantly done by men being graded higher than jobs predominantly done by women.
4.    Women could be less likely to receive, or receive lower amounts of, additional payments such as allowances, payment for additional responsibilities, recruitment incentives or market supplements.
5.    There could be differences in the contractual hours of different occupational groups in jobs evaluated to be at the same grade.
6.    There could be differences in pension entitlements or retirement ages between different groups with different representations of men and women.

Two factors which could influence gender pay gaps but which are not equal pay issues are:
1. Women might be more likely to leave giving a greater proportion of women on lower points in the grade or men might be more likely to leave, for example, for higher graded positions, leaving proportionately more women at the top of the grade.
2. Women may have been entering jobs at this level in increasing numbers in recent years leading to a clustering of women at lower points in the grade.

We thus have factors which are equal pay related that will be reflected in gender pay gaps, such as lower starting salaries, factors which are equal pay related that will not be reflected in equal pay gaps, such as biases in the job evaluation scheme, and factors that are not equal pay related but will affect the gender pay gap.

Figure 1 shows a distribution of women on a nine point scale, perhaps arising as a combination of women ending up with lower starting salaries, being less likely to apply for promotion and men leaving for better paid positions. The trend line has a slope of -0.0425, so the proportion of women falls by about 4 percentage points per scale point. If there are the same number of people on each salary point and each salary point is 2.5% higher than the one below then this distribution leads to a gender pay gap of 2.8% and no investigation is required. If, however, each salary point is 5% higher than the one below the gender pay gap is 5.7% and further investigation is required although the underlying biases that led to this situation would be the same in both cases. Both gaps are statistically significant if there are twenty or more people on each salary point.

Figure 2 shows a similar distribution on a fourteen point scale. The trend line has a slope of -0.0312. In this case the gender pay gap is 5.1% when the increment from one scale point to the next is 2.5%. This gap is highly statistically significant if there are at least twenty people on each scale point. Note that if this grade was split into two grades of seven scale points the gender pay gaps would be 1.6% for each grade though the men and women would be being paid the same salaries as before.

These examples show that the same underlying biases can give rise to gaps that may or may not be regarded as practically important depending on the particular salary structure.

As another example, suppose you have 100 men doing a particular job at a particular grade with an average salary of £25,000 and 100 women doing the same job at the same grade who would have the same average salary except that a policy of taking existing salary into account when determining the starting point in the grade has led to twenty women who returned from a career break being paid 6% less than similarly qualified men or women who had not taken a career break. The average salary for all the women is £24717, a gap of 1.2%. This is not likely to be statistically significant (on a ten point scale with an average of twenty people per scale point with a 3% increment there is a 15% chance of men’s average pay exceeding that of women by at least 1.2%) and nor is it large, though the twenty affected women might disagree.

This example shows that relying on the gender pay gap to identify anomalies could result in failing to detect substantial biases.

This still leaves the question: what is a practically important gap? There does not seem to be a good answer to this question. Is it acceptable for women to paid one scale point less than comparable men as long as the gap between scale points is less than 3% but not acceptable if the gap between scale points is greater than 3%? Is exactly the same bias acceptable if it occurs over two grades with a small number of steps but not if it occurs over one grade with a larger number of steps? Is it acceptable for 50% of women to be paid one scale point less than comparable men but not for 100% of women? What are the criteria for practical importance? Practically important to whom? The women earning 6% less than they might have been? The employer who might face an equal pay claim?

Does this mean carrying out an equal pay audit is a waste of time? No, it does not. An organization that measures its gender pay gaps for groups identified as doing the same or equivalent work or doing work of equal value is more likely to identify anomalies than one that does not. What it does mean is that organizations should examine their pay schemes and identify how anomalies could occur, for example, that people returning from career breaks tended to be placed on lower starting salaries thus tending to disadvantage women, and monitor those points directly regardless of whether or not they have observed substantial gaps.

An effective equal pay audit would:
•    Describe the way the institution sets pay or, at the very least, refer to another document that does so.
•    Identify the processes where bias could occur, e.g. setting starting salaries.
•    Monitor those processes.

 It could be that in a system where individuals negotiate their own pay or individuals’ line managers have a large say in setting performance pay that the best way of monitoring is to measure the gender pay gap. In institutions with job evaluation schemes and set pay scales it would be better to monitor starting salaries and progression directly to avoid potential bias being masked by other factors that affect the pay gap.

Processes that could introduce bias include the job evaluation scheme, if one is in place. The EHRC has pertinent advice on how to check that a job evaluation scheme does not itself inadvertently discriminate against women.

Has your institution carried out an equal pay audit? Does it meet the above criteria? Do you think it should? Is there anything you can do about it if it doesn’t?

Tuesday, November 23, 2010

Women's Networks

I have been involved in women's networks in science either passively or actively for about twenty-five years. These are my thoughts on women's networks.

Why do we need them? What are the benefits?
Women's networks can:
•    Provide a safe and supportive environment for women to exchange experiences.
•    Provide a means for women to exchange information.
•    Build women's skills by giving them the opportunity to take on various roles within the network.
•    Increase women's visibility.
•    Enable women to push for change more effectively.

How can they be effective?
•    Provide a regular programme of events to maintain momentum. It does not matter if attendance at some events is low. Just getting the email saying that something is happening reminds people that the network is active.
•    The best publicity is word of mouth. Women who have had a good experience tell their friends.
•    Maintain a positive focus.
There are many types of events that women's networks can run, for example, speaker events, career-focussed events and social events. Generally the types of events a network runs will depend on the interests and enthusiasms of its members. Although, in principle, women's networks provide a way for women to make their views on existing policies or proposed changes to policies known, in practice, whether or not this happens depends on whether an individual feels strongly enough about the issue, and has the time and energy, to do something about it.

In my experience members of women's networks are not interested in formal structures. They prefer informal arrangements to prescriptive specifications. It is better to make things happen and then worry about structures. Nevertheless, in my experience there are minimum requirements if the network is to be more than a handful of friends who happen to meet fairly regularly. There needs to be someone who is visibly responsible for the network. This person will often be known as the Chair of the network. There also needs to be a treasurer, someone to keep records and someone who is responsible for communicating with members, for example, via a newsletter. These responsibilities do not need to be held by different people but I think it helps if there are identifiable people taking responsibility for these areas. It gives people a point of contact if they have a query or suggestion or if they want to invite a representative of the network to an event. It is also important that the network does not become reliant on one or two people otherwise it can collapse if one of them gets a new job, has a baby or moves away. This means there has to be a way of ensuring new people take up positions of responsibility. Having an ‘incoming president’ or ‘incoming chair’ position is useful for ensuring continuity.

In order to function effectively a network needs some resources. Obviously the time and energy of those who organise events are essential. Women's networks within organisations need to be properly resourced either with money or with in-kind assistance such as free meeting rooms. The work that people put into such networks needs to be recognised as part of their job and not seen as an optional extra. A women's network can increase productivity, for example, by helping women find effective solutions to difficulties they may be experiencing. For women's networks operating outside of a single employer the situation is more difficult, although they play a very important role in broadening the range of experiences available to their members. Such networks have to have sufficient resources to pay for venue hire and refreshments as well as, in some cases, expenses for speakers. These resources have to found either from members, potentially deterring some women from participating, or through sponsorship, which can be time-consuming to find and is especially difficult for women with day jobs who do not necessarily have the time to contact and follow-up potential sponsors.

Exclusive or Inclusive
Every women's network I have been involved with has, at some point, discussed the issue: is it just for women or can men join too? This has usually been a question of principle rather than practice since men usually self-exclude anyway. One one hand  women's networks need to provide a safe and supportive environment for women. On the other many of the issues that constrain women's full participation in employment are never going to be resolved by groups of women talking among themselves. We need men to get involved. In my view a safe and supportive environment means one in which the discourse is set and shaped by women not one from which men are excluded.

What would help?
•    Money – of course. Ideally support would be aimed at helping the network achieve its objectives but inevitably a sponsor tends to want the network to help achieve the sponsor’s objectives.
•    Recognition - line managers making sure women know about opportunities to participate in women's networks and senior managers and influential members of the business community promoting the benefits of women's networks.
•    Capacity building in skills such as effective use of the web from on-line booking to running a discussion forum, running effective meetings, and fund-raising.

Wednesday, November 17, 2010

The Pace of Change

One of the indicators of the position of women in academic science is the proportion of women among academic staff in STEM departments. How fast can this indicator change?

The first constraint is the number of vacancies available for women to be appointed to. For example, if a department has a turnover of 5% per year and the number of academic staff is growing at 2% per year then the overall vacancy rate is 7% per year.

The next most important constraint is the proportion of women in the pool of potential applicants. If the pool of potential applicants is 50% women and no women leave the department then a department with a vacancy rate of 7% could achieve an increase in the proportion of women of 3.5 percentage points per year. In these circumstances a department could get from 25% to 50% women in 7-8 years. However, if turnover was around 3% and the number of academics was static then the best the department could achieve, if no women leave, is a growth in the proportion of women of 1.5 percentage points per year. At that rate it would take 17 years to get from 25% to 50%. Of course, this might well be an underestimate since it is unlikely that no women would leave over a seventeen year period.

There is an additional complication. Suppose a department is able to make six appointments over a three year period and it makes the appointments from a pool that is 50% women. If recruitment is fair with respect to gender then the probability distribution for the number of women appointed will be a binomial distribution with N=6 and p=0.5. This gives a probability of 0.31 of appointing exactly three women, a probability of 0.34 of appointing two or fewer women and a probability of 0.34 of appointing four or more women (probabilities do not add to one due to rounding). Hence for time periods in which a small number of appointments are made fair recruitment processes could easily result in apparent growth rates between 2/3 and 4/3 times the expected rate.

1.    There are limits to how fast the proportion of women among academic staff in STEM can increase. Growth rates of a few percentage points per year are not unreasonable.
2.    Estimating the long-term growth rate from measurements made over short periods is futile.

The second conclusion implies that simply collecting data on the proportion of women among new appointees is unlikely to reveal inadvertent bias in the recruitment process. While these data are necessary it is also necessary to assess the recruitment process against best practice established by large studies, such as that described in the US National Academies Report Gender Differences at Critical Transitions in the Careers of Science, Engineering and Mathematics Faculty. (A briefing on the report is available from the pages of the National Academies Committee on Women in Science, Engineering and Medicine.)

Monday, November 8, 2010


I have just read two very different books: Randy Olson's 'Don't be such a scientist' and 'Healing our History: the challenge of the Treaty of Waitangi ' by Robert and Joanna Consedine.

Olson's book is an easy read - short, breezy, anecdotal but making the very important point that if we want to engage non-scientists with science we need to have good stories while retaining factual accuracy. Anyone who is involved in science communication should read this book but for me it also sparked some thoughts about how we communicate about women in science. For example, much of our communication is directed to scientists, people to whom accuracy matters, the sort of people who feel the need to point out to an actor speaking enthusiastically about spotting whales that there are no gray whales in the Atlantic or who are worried by the fact that in James Cameron’s original version of Titanic the ship sinks under southern hemisphere stars. Are we careful to make accurate statements? Do we play to the strengths of academics or do we regard them as problems? A male participant in the University of Michigan’s STRIDE programme commented on its style saying it followed ‘pure academic principles of engagement … It was clear that they wanted you to study, work, read, form opinions, validate or invalidate current approaches … to become educated.’ (Reference 1) Are our efforts concerned with engaging scientists as scientists or are we uncomfortable with argument and dissent?

'Healing our History' was a difficult book for me as a Pakeha to read. Some background: in 1840 the British government signed a treaty with the Maori people of New Zealand. The representatives of the British government and successive New Zealand governments then spent the next 140 years ignoring the provisions of the treaty and exploiting the Crown’s position as the sole purchaser of Maori land, while promoting the view that if Maori were disadvantaged then it was their own fault and the solution was for them to become Europeans. Requests for restitution for the failure to abide by the treaty are still spun as ‘demands for handouts’.

I would hesitate to draw parallels between the situation of Maori in New Zealand and women in science. I think the histories and consequences are quite different. Nevertheless, I believe there are lessons from the Consedines’ book that can be applied to thinking about women in science.

Firstly, I now understand the attraction of ‘wilful ignorance’. If you take no steps to understand the facts then you can comfortably deny that there is a problem. Those who refuse to collect data on the grounds that they already know that their workplace is fair may fall into this camp. Knowing that there is a problem demands a response, even if that response is to decide to do nothing.

Secondly, Robert Consedine runs workshops on Treaty issues. The initial workshops are run in parallel: one for Maori with a Maori facilitator and one for Pakeha with a Pakeha facilitator. Prior to attending a workshop, many people are uncomfortable with this arrangement, which they feel smacks of separatism. However, experience has shown that it is useful for Pakeha to be able to express their fears and misconceptions in a safe environment and it is useful for Maori to be able to explore their identity as Maori without being regarded as representative of all Maori. Before attending a parallel workshop only 16% of participants believed they were needed. After attending a workshop 90% thought they were needed. The need for women to have a safe environment in which to express their concerns has long been recognized. What about men? Do they have a safe space in which to express their concerns and fears?

A common reaction to the workshops was puzzlement that a group of Pakeha were teaching the Treaty of Waitangi. The idea that Pakeha would take responsibility for learning and teaching Treaty commitments was mystifying. How many men are willing to take responsibility for promoting gender equality? How often is it seen as a women’s issue? What does ‘take responsibility’ mean? The Consedines quote Jorge Rosner: ‘Responsibility literally means “the ability to respond”. You only respond when you are fully aware of you behaviour and your choices, then, on the basis of your awareness, you can freely choose what to do.’ (Reference 2) Taking responsibility does not mean accepting guilt for what has happened in the past. It means looking at the current situation, asking what needs to be done, and doing it.

Robert Consedine also writes ‘I encourage people to live with the questions, as a ‘solution focus’ is often a barrier to change in this arena.’ This is a difficult concept for those of us in a ‘What’s the question? Here’s the answer. Move on’ culture, especially those of us trained in using reductionist techniques to solve problems.

So, two very different, but challenging and thought-provoking books.

Thursday, November 4, 2010


Men do not let anyone seize their estates, and if there is the slightest dispute about their boundaries they rush to stones and arms; but they allow others to encroach on their lives - why, they themselves even invite in those willing to take over their lives. You will find no one willing to share out his money; but to how many does each of us divide up his life!

De Brevitate Vitae (On the Shortness of Life) Lucius Annaeus Seneca (c. 3 BC - 65 AD) Roman philosopher, statesman and dramatist Translated by C. D. N. Costa (1997), Penguin Books - Great Ideas

How good are you at setting boundaries on other people's access to your time?

The picture shows two kereru (New Zealand wood pigeons) in a tree. It was taken from our living-room window. If you want a link to the subject of the post I guess it is a reminder to look out the window from time to time.