The table below shows ten headline policies in the 2019 Conservatives and Labour manifestos (Brexit aside), as well as some of my own top picks, in no particular order
| Conservatives | Labour | Me |
| Increase spending on the NHS | A green industrial revolution, including more funding for low carbon technology and more state control of climate and energy policy | Encourage clean energy innovation and expand on and strengthen the UK’s mix of flexible regulations and carbon pricing. |
| Additional funding of social care and a cross-party resolution on how to improve social care | Expansion of public transport | Relax restrictions on house building in urban centres, taking planning decisions out of the hands of local property owners. |
| School funding | Increase funding for the NHS and social care | Introduce a land value tax, or common ownership self-assessed tax |
| Cut national insurance or payroll taxes | A national education service to provide lifelong vocational technical and academic education | Abolish stamp duty |
| Additional funding for childcare | Spend more on policing | Fund greater tax credits for those on low incomes by increasing income tax on the very wealthy |
| Increased funding for the police | Increase funding of, and devolve power to, local councils | Increased high skilled immigration |
| Measures to cut utility bills | Increase the minimum wage and expand employment rights, including a 32 hour week in ten years | Introduce responsive road pricing |
| A points-based immigration system | Increase legal guarantee of various forms of identity inequality | Increase funding for public transport, especially in the North. |
| Upgrading rail systems in the north | Scrap universal credit and work to develop a viable alternative | Relax drug laws. |
| Net zero economy by 2050 | Large increase in building of social housing | Establish a new government body for socially beneficial high-risk science projects |
Now I am going to cross out the policies that have not, in any relevant social context, been tested by a randomised control trial. In bold are the policies that definitely cannot, for practical or ethical reasons, be tested by RCTs.
| Conservatives | Labour | Me |
If you were feeling very ambitious, you could test the effect of increased funding for schools and the health service with an RCT – maybe employ the new nurses and teachers in a treatment region and compare to a control region. However, the statistical power of the RCT would not be very good, and even if the whole government became convinced of the value of this, it would be political suicide.
What becomes clear from performing this exercise is that RCT-evaluable policies are not now, nor will they ever be, where the action is when it comes to the big UK policy questions. The highest impact things one would want to do have not been tested by RCTs and there is no way they could ever be in the future. If we were allocating the effort of economists in the UK, less than 1% of it should focus on things that can be tested by RCTs.
This raises the question – why is so much of the economics profession and philanthropy focused on RCT-evaluable things when their attention turns to low- and middle-income countries? What is the difference between rich and poor countries that makes RCTs the right approach in one context but not another?