Question: We asked, "John saw 80 monarchs and Mary saw 79, but Mary saw a stronger migration. What information is missing and why does it matter?"

 

 

Answer:
We need to know the length of time each person was watching. We want to know how many monarchs per minute (or per hour). This gives us a standard way to compare observations.

Example:
Let's add an observation time to this example and see why it matters:

Let's say John saw 80 monarchs. He was watching all day, for 8 hours. This means John saw 10 monarchs per hour.

Let's say Mary saw 79 monarchs. She was watching for only 30 minutes. This means Mary saw 158 monarchs per hour.

Even though John saw more monarchs the migration was much stronger where Mary was watching!