Module 11
3 min
STDEV.P & STDEV.S
Measure how spread out your data is
STDEV.P & STDEV.S
Standard Deviation = How spread out are your numbers?
What is Standard Deviation?
Low = Numbers are close to average
High = Numbers are spread out from average
| Data Set | Average | Spread |
|---|---|---|
| 10, 10, 10, 10 | 10 | Low (all same) |
| 5, 10, 15, 20 | 12.5 | High (spread out) |
2 rows
Two Types
| Function | Use When |
|---|---|
| STDEV.P | You have ALL the data (Population) |
| STDEV.S | You have a SAMPLE of data |
2 rows
Not sure? Use STDEV.S (most common)
STDEV.S (Sample)
=STDEV.S(range)
| A (Scores) |
|---|
| 70 |
| 80 |
| 90 |
| 75 |
| 85 |
5 rows
=STDEV.S(A1:A5) → 7.91
Scores vary about 8 points from average.
STDEV.P (Population)
=STDEV.P(range)
Use when you have everyone's data.
Example: All 5 employees' salaries (not a sample)
=STDEV.P(A1:A5) → 7.07
Real Life Examples
Test scores spread:
=STDEV.S(B2:B50)
Employee salary variation:
=STDEV.P(C2:C20) (if all employees)
Product price range:
=STDEV.S(D2:D100)
Quick Comparison
| Function | Full Form | When to Use |
|---|---|---|
| STDEV.S | Standard Deviation Sample | Sample data (most cases) |
| STDEV.P | Standard Deviation Population | All data available |
2 rows
Summary
- STDEV measures data spread
- STDEV.S → for sample data (common)
- STDEV.P → for all data (population)
- Low value = data close together
- High value = data spread apart