A speed test that said 900
A technician tests the Wi-Fi. Her laptop shows 900 Mbps. She tells the head teacher it is brilliant.
But the school's internet line is 100 Mbps. The test cannot be right. Results need checking before anyone believes them.
By the end of this lesson
Note
I can use checks to decide if a test result is believable and accurate.
Key words
| Word | What it means |
|---|---|
| Believable | you have good reason to trust it |
| Accurate | close to the true value |
| Bias | an unfair lean in how you chose your inputs |
| Logical reasoning | thinking step by step to check if something makes sense |
| Subject matter expert | a person who knows the topic very well |
| Test plan | a table that lists every test before you run it |
The cells students fill in are left blank in this preview.
Starter
Have a go
Starter
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Check with logical reasoning
Ask two questions.
First, are the inputs fair? Did you test every relevant case, and without bias? Testing Wi-Fi only in the empty hall at 7am is biased. Test classrooms, busy times and far corners too.
Second, does the result make sense for the inputs? A line of 100 Mbps cannot give 900.
Worked example: Wi-Fi tests around a school
| Place and time | Measured | Believable? | Reason |
|---|---|---|---|
| Empty hall, 7am | 85 Mbps | Yes, but only part of the picture | Best case, so biased if it is the only test |
| Busy classroom, 10am | 22 Mbps | Yes | Many users, so slower is expected |
| Far corridor, 1pm | 0 Mbps | Needs checking | May be a dead spot or a faulty test |
| Staff room, 3pm | 340 Mbps | No | Above the 100 Mbps line, so impossible |
The cells students fill in are left blank in this preview.
Check
Have a go
Check
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.