Checking each other
Show on a big screenTwo groups count drops of water on a coin. They get different numbers.
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The idea
Different numbers do not always mean a real difference. Even one group gets a different count each try.
A trial is one try. An average is the total of all trials divided by their number.
The jump inside one group is the highest trial minus the lowest. The gap is how far apart the two averages are. A gap under a third of the jump is far below it.
Compare the gap between two averages with the jump inside one group. A gap far below the jump gives no sign of a difference. Repeat the test to be sure.
Take five trials each. A gap above the jump means a real difference.
- Group A's trials, marked with an average.
- Group B's trials, marked with an average.
- The gap between the two averages is small.
- It is far below the jump inside a group. No sign of a difference.
Another group repeats the test and agrees. Now the result is more trusted.
Try the lab to finish this lesson.