Skip To Content
Cambridge University Science Magazine

Most people studying a STEM subject have probably heard of the ‘leaky pipeline’. This metaphor describes how women and people from minority groups are progressively lost from STEM subjects at each stage of the educational system. However, recent criticism has argued that this metaphor may actually perpetuate the very dilemma it is trying to address. Why do people leave STEM fields, and what are the problems with the pipeline metaphor? This article will discuss these issues, as well as some alternative metaphors and intervention strategies proposed to ‘plug the leaks’.

CONSTRUCTING THE PIPELINE | The concept of a ‘STEM pipeline’ first emerged in education policy in the 1970s, when Western countries became concerned about the number of qualified scientific professionals needed to keep pace with the technological advancements of other geopolitical powers. The metaphor describes how people can be funnelled through an education system which begins at primary school, progresses to university, and eventually drops them into a STEM career.

In later decades, however, it became obvious that not everyone who enters the pipeline makes it out the other end. In particular, women and people from minority groups become progressively under-represented in STEM fields as they move through the pipeline. For example, while the number of male and female students studying science at GCSE level is roughly equal, girls make up only 20% of students studying A Level Physics. Recent surveys by the Royal Society show that only 9% of STEM professors in the UK are female, and — shockingly — less than 0.1% of STEM professors are Black. While we focus here on barriers faced by women and ethnic minorities, there is also significant under-representation of people with disabilities, those who identify as LGBTQIA+, and those from low socio-economic backgrounds. Thus, the pipeline grows smaller and smaller, leaking people at every junction, eventually releasing a small trickle of people into a STEM career.

WHEN AND WHERE ARE THE LEAKS? | Do women and those from minority groups choose not to pursue a STEM career, or are they actively excluded from the system? As with most equality, diversity, and inclusivity issues, it is a bit of both. In early childhood, girls and boys are equally likely to be interested in science. In fact, girls routinely outperform boys in science GCSEs and A Levels. But interest and ability do not always translate into the belief that one can become a scientist. Children are often (wrongfully) taught that a true scientist must be ‘brilliant’, a ‘genius’. However, a study from NYU found that by the age of seven, girls are far less likely than boys to describe themselves or other girls as brilliant, and therefore do not see themselves as smart enough to pursue a STEM career. These misconceptions are clearly amplified by the Western media: compare the fame and recognition of prominent white male scientists like Brian Cox and David Attenborough to the brilliant but less famous Hannah Fry, Chris Jackson, and Maggie Aderin-Pocock.

For those who choose to study science at university, studies have repeatedly shown that if students do not see themselves represented at higher levels of academia, they are much less likely to continue in that field — we previously noted the lack of diversity in UK university faculty, which is echoed in most Western countries. Further barriers to progression in academia include the systematic bias against women in the success of grant applications, citation metrics, and recommendation letters: in one study of applicants for Earth Science positions at a US university, female applicants were only half as likely to receive ‘excellent’ recommendation letters versus ‘good’ letters, compared to male applicants.

HOW DO WE FIX THE LEAKS? | To recruit and retain women and other minority groups in STEM subjects, we should begin early in a child’s education, engaging the students in science by forming connections between the classroom, universities, and community organisations. A great example of this is Project Exploration in Chicago, a non-profit which targets Black and Latino secondary school students, particularly girls. Scientists run activities related to their work and share personal stories while building relationships with the students. The program provides extra-curricular engagement for the students and raises awareness of different science subjects and careers. A recent review found that 60% of Project Exploration’s alumni who graduated from university had a degree in a STEM-related field, compared to the US national average of 20%.

To retain under-represented groups in tertiary education and beyond, we need to create an environment in which everyone feels welcome, supported, and able to perform to the best of their abilities. One way to retain minoritised undergraduate and postgraduate students is to involve them in mentoring or peer network programs, which provide support structures while remaining separate from the formal hierarchy of academic research. For those at faculty level, universities must accommodate major life events by providing adequate maternity leave, part-time work, and opportunities to re-enter the academic community after pursuing other ventures.

If educational entities wish to diversify their STEM populations then they must also consider intervention as an intersectional issue: someone can have multiple identities (ethnicity, gender, or sexual orientation, for example) which place them in the minority. A recent report from Texas A&M University suggests that to create a better working environment for women of colour in STEM faculties, universities should enforce mandatory implicit bias training for all staff, diversify their hiring committees, and undertake targeted hiring of women of colour.

THE PERPETUATING PIPELINE | The concept of the leaky pipeline has helped to highlight under-representation in STEM fields, but recent commentary has suggested that this metaphor may actually do more harm than good. For a start, the pipeline perpetuates the concept of a narrow and linear educational pathway, which excludes some and accelerates the careers of others. If people do not enter the STEM pipeline in childhood, should that stop them from pursuing a STEM career later in life? Secondly, the nature of modern STEM education and careers is much broader than it was in the 1970s. A 2014 study found that the trajectory expected by the pipeline (studying science at school, undergraduate, and often postgraduate level) failed to describe the experience for nearly half of those who became scientists in the US. Another issue is that anyone who “leaks” from the pipeline is seen to have been failed by the system. Angela Merkel obtained a doctorate in quantum chemistry before choosing to enter politics: would she be considered a failure of the STEM pipeline?

An alternative analogy, offered by a collective of US Earth Science academics, is to imagine the STEM educational system as a braided river. In nature, a braided river is a wide, shallow system made of interwoven and changeable channels. Over time, the movement of water changes the shape of the channels and supports ecosystems. Imagining the STEM system as a braided river shows us that there are multiple changeable pathways to a career, with unusual entry points, evolving career goals, and the opportunity to change pace and direction. This metaphor represents an alternative educational system which can be inclusive, responsive, and representative of transient modern careers.

There have been many great achievements in increasing representation in STEM over the last few decades: for example, female students now outnumber male students taking science subjects at A Level. But ultimately, to create a STEM environment which is inclusive and supportive of everyone, we must reconsider how we view the STEM educational system and workforce. Promoting a narrow and rigid pipeline will only continue to exclude the diversity of thought and experience which is so necessary for the advancement of science

Lizzie Knight is a 2nd-year PhD student in Earth Sciences at Fitzwilliam College. Artwork by Mariadaria Ianni-Ravn.