Hello all- I feel like there is an easy solution to this but I just can't see how to do it. I have data representing hours of observation in a medical ICU, across 4 hospitals. One observation=one hour. Within that hour, there will be staff coverage from between 1 and up to 8 nurses. These are listed as variables nurse_ID_1, nurse_ID_2, etc. The are between 20 and 28 different nurses providing coverage over the study period, depending on the hospital. I have a separate data set which contains information on total years of experience for each nurse, by nurse ID. I would like to generate a variable in my main data set which represents total number of years of experience available from the nursing staff for that shift hour. Any thoughts on how?