7th Grade · Statistics & Probability
Variability
7.SP.A.2
Definition
A measure of how much data values differ from each other. High variability means data is spread out; low variability means data is clustered. Measured by range, MAD, or IQR.
Teach it
Where it is taught, with guided notes, practice, homework, an exit ticket and an interactive Teacher Deck.
Examples
- Set A {5,6,6,7,7,7,8,8,9}: range 4, MAD ≈ 0.9 — low variability, tightly clustered.
- Set B {0,0,0,0,7,10,14,14,18}: same mean 7, but range 18, MAD ≈ 6.2 — high variability.
Key rule
Same mean can hide very different spreads — always check variability too.
Memory hook
How spread out, not just where the center is.