Your team finishes a quiz app. You think it is great. But what do the users think?

You could ask them. You could watch them. You could count how often they use it.

Each way gives you a different kind of answer. A good developer knows many ways, and chooses the right one.

load_times = [2, 3, 2, 8, 3, 2, 4, 9, 3, 2]   # seconds

total = sum(load_times)
average = total / len(load_times)
slowest = max(load_times)
slow_pages = 0
for t in load_times:
    if t > 5:
        slow_pages = slow_pages + 1

print("Average:", average)
print("Slowest:", slowest)
print("Pages slower than 5 seconds:", slow_pages)

# Change a number and run it again.

In an observation you watch a user try the app. You say nothing. You do not help.

You fill in an observation record. It says the task, the time taken, what went wrong, and what the user said. Watching shows problems that people forget to tell you about.