$stdDevPop/$stdDevSamp
Reference group: Accumulators and ranking
What it does
Computes population or sample standard deviation.
Syntax
Accumulator expressions
Use case
Measure numeric spread.
$stdDevPop/$stdDevSamp: practical example
{ $group: { _id: "$class", spread: { $stdDevPop: "$score" } } }💡 Explanation
Computes population or sample standard deviation.
When to use it
Measure numeric spread.
Key Takeaways
- Computes population or sample standard deviation.
- Typical use: Measure numeric spread.