In principle, this is a question there could be an objective, factual answer to. Social scientists have been collecting data for 60 years on what makes people happy. Simply, people are asked how they think and feel about their lives. While people do differ in what makes us happy, we differ less than we’d think. Just as no one wants to be in pain, nearly everyone enjoy spending time with their friends and doing fulfilling work. Using the data on happiness, can we establish which polices should make people happier on average. In theory, we could audit the manifestos’ impact on happiness just like the Office of Budget Responsibility does their spending promises.

In practice, it’s not so simple. Doing a precise calculation is immensely complicated. What we can do, and I’ve done here, is a quick and dirty analysis. On the basis of the happiness evidence, we can divide policies into three groups.

The first is those policies that don’t clearly matter to happiness. The top examples are policies to bring economic growth and anything to do with the deficit. Perhaps the most famous result in the happiness data – known as the Easterlin Paradox, named after the economist who noticed it – is that people in developed countries have been getting wealthier, but not any more satisfied with their lives, since World War Two.

While this may seem mysterious, it’s got a fairly obvious explanation. Our happiness is determined by how we feel about what we pay attention to. We adapt to unchanging circumstances and stop paying attention to them. On a daily basis, ordinary people might worry about their work, their family, their health and their commute. What they don’t do is wake up every day a feel grateful they aren’t in a North Korean labour camp. In the same way, rich people don’t focus on how rich they are. That’s why increasing average wealth won’t make the country happier. We can’t neglect economics altogether (as the Greeks or the Zimbabweans could tell us) but wealth doesn’t matter nearly as much we think it does.

Also in this category are foreign affairs, immigration and education. Today, how long did you think about Isis or foreign immigrants for? Was it longer or shorter than you spent thinking about what you should have for lunch? Exactly. Equally, while different education policies may make people smarter, it’s less clear how they’ll increase national happiness. The rule of thumb is that if a policy wouldn’t change something that you’ve done or thought about today, it doesn’t matter.

The second group is policies that do affect happiness, but spending money on them won’t increase it overall because that means you’re taking money from something else. Examples of this include things like spending more on physical health, transport or law and order. If the Tories create 5,000 more doctors, but won’t spend any more overall, and that money comes out the police force or rail infrastructure, the changes cancel each other out.

The third are policies that are really important happiness because they change how people experience their lives. Policies that increase support for mental health and social care, reduce unemployment and lift people out of poverty are those that matter most. To realise why, think of it this way: while breaking a leg might be painful initially, in the modern day it’s really just an inconvenience. However, being depressed, being unemployed or being in poverty are not things you adapt to and stop thinking about.

So, who should you vote for? It depends on your economic views. If you think money grows on trees, vote Green: their support for a guaranteed income, amongst other things, will increase happiness in the short term. If you don’t think money does, vote Lib Dem: their £3.5bn commitment to mental health is the policy with the biggest positive happiness impact. Just behind them are Labour, with the Tories and Ukip’s more right-wing welfare policies putting them in fourth and fifth.