3 years is deceptive - in an exponentially growing company, the majority of employees are fresh, pushing the average tenure low. The relevant number is "length of tenure at time of severance", which I believe skews much higher. Any company seeing 30% churn is having a bad, bad time.
What do you mean? Every employer I've worked for had data for the starting date of their employees, when someone leaves you have an end date of employment. It's a pretty simple metric to calculate.
