How do you make your customers happy? Make your employees happier.

Recruitment website Glassdoor just published some research which could be a quick win for marketing people everywhere. Their data shows a direct correlation between employee engagement and customer satisfaction. As you’d expect, it’s most pronounced in companies where employees interact directly with lots of customers: hospitality and retail, for example. It’s less marked in manufacturing. Even so, Glassdoor’s Chief Data Officer says that on average there’s a 1.3% uplift in customer satisfaction for every 1% increase in employee engagement.

In retail, the ratio is more like 3.2% for every 1% uptick in employees’ motivation. When you think about companies with happy employees (Trader Joe’s, Ritz-Carlton, Southwest Airlines), they’re often companies we’re fond of as customers.