I am trying to estimate an overhead due to the effect of interruptions on an employee.
For example: Imagine an employee who is responsible for repair services. He gets called on a daily basis by external people who have questions, like to get advice etc. In addition the employee now and then gets called to help out in meeting preparations etc. All these "side tasks" appear as interruptions since they are not the employees main task but there is no one to do them other than him.
Now I am looking for studies that have researched the effect of such interruptions on the effectivity and efficiency of work. The goal is to get a percentage value of the time he is spending on their core tasks to estimate the interruption effect in hours. The result should look something like this:
Time for core task: 100 h Interruption Overhead: 10 % Interruption time: 10 h
The idea is to estimate if interruption is acceptable for a given workload or needs to be reduced by means that depend on the given situation.