Not specifically in this context, but I have experience in various diversity programmes. One thing to highlight:

When you frame the problem as ‘we need more women’ (or more people of a particular ethnicity, or sexual orientation, or whatever) then this immediately devalues people in the group that you are trying to target. We did a lot of work at Microsoft to try to stop senior leadership boasting at all-hands meetings that they’d hired more women, because women in the audience immediately thought ‘was I hired just because I’m a woman?’ And then thought ‘do my colleagues think I was hired because I am a woman?’ Which then immediately undermines them in their job.

Not having women in leadership positions is not the problem, it is a trailing indicator of the problem. The root problems are likely to be things like:

• You are recruiting from places women avoid, or which favour men.
• You are recruiting via your networks, where women are underrepresented.
• You are encouraging an in-group culture that makes everyone not in that group feel excluded and this disproportionately affects women (you will also be losing other people for the same reason).
• You are organising things at times that are inconvenient for people with carer responsibilities, which disproportionately affects women.
• You are looking for people who have a lot of free time and this systematically excludes a load of people (you can’t fix this as a volunteer project, but you can push for government equity initiatives).

Remember: your goal is to find the best people. The fact that roughly 52% of the population are self-deselecting before you even get to evaluate them on relevant metrics is a significant indicator that you are failing at this. Keep that framing in mind.