Excel Count distinct numerical values if string condition matches

Question

On one tab, I have a list of the names of my employees. On another tab, I have orders that my employees have shipped, together with the month they shipped them, going back a full year. To get the average quantity of products supplied per employee each month, I must first know how long they have worked for the company. Therefore, I want to create a formula that basically says, "Give me the count of the specific amount of months they've been shipping things."

Sample employee data:

And here's the sample data on the individual shipments:

So in order to determine that Joe Smith ships an average of 83.3 items per month, I need to know that he sent those 250 products over the course of three separate months. Again, I can't just divide them all by 12 and need to know how many months they were shipping products because there were so many new hires in the past 12 months.

Answer 1

FILTER Shipper and Month based on Employee name in the Shipper column. To obtain just unique data (name + month number), apply UNIQUE to the filtered array. To calculate active months, use COUNT. Distribute the Products Sent by it.

Result: