NORM.DIST
The normal distribution of a mean and standard deviation at a value, as a density or a cumulative probability.
Group: Statistics. Compatible with DAX.
Syntax
NORM.DIST ( <X>, <Mean>, <Standard_dev>, <Cumulative> )| Parameter | Type | Description |
|---|---|---|
X | Number | The point to read the curve at. |
Mean | Number | The centre of the normal curve. |
Standard_dev | Number | Its spread, above 0. |
Cumulative | Boolean | TRUE for the cumulative probability, the chance of a value up to x; FALSE for the density at x. |
Returns
Number. The normal density at x, or the probability of a value no larger than x.
Remarks
- For mean 0 and standard deviation 1,
NORM.S.DISTneeds only x. - A standard deviation of 0 or less is an error.
- 1 − NORM.DIST ( target, mean, spread, TRUE ) is the chance of going above a target when the outcome is roughly normal around a forecast.
Examples
Density and cumulative probability
EVALUATE
ROW (
"Density", NORM.DIST ( 42, 40, 1.5, FALSE ),
"Cumulative", NORM.DIST ( 42, 40, 1.5, TRUE )
)| Density | Cumulative |
|---|---|
| 0.109340049783996 | 0.908788780274132 |
How often a month sells more than 55,000 liters
The months' mean and spread, read as a normal distribution, against how many months did.
EVALUATE
VAR Monthly = ADDCOLUMNS ( VALUES ( Sales[Month] ), "Liters", [Liters sold] )
VAR Mean = AVERAGEX ( Monthly, [Liters] )
VAR Spread = STDEVX.S ( Monthly, [Liters] )
RETURN
ROW (
"Chance above 55,000", 1 - NORM.DIST ( 55000, Mean, Spread, TRUE ),
"Months above 55,000", COUNTROWS ( FILTER ( Monthly, [Liters] > 55000 ) ),
"Months", COUNTROWS ( Monthly )
)| Chance above 55,000 | Months above 55,000 | Months |
|---|---|---|
| 0.242119368563611 | 9 | 36 |
The normal curve says about one month in four; in fact 9 of 36 did.