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3.18. Cumulative Probability

Applies to: @RISK 5.x and newer

Excel has functions like NORM.DIST (NORMDIST in older Excels) to return the cumulative probability in a normal distribution. Does @RISK have anything like that?

Yes, @RISK has functions to find the cumulative probability for any distribution. Instead of a separate cumulative-probability function for each distribution, @RISK uses the same function for cumulative probability of any distribution.

Actually, there are two functions, one to obtain simulation results and one to query the theoretical distribution.

Instead of the probability from –∞ to an x value, how can I get the probability between two x values?

Just subtract the two cumulative probabilities. For example, the cumulative probability of cell PQ456 between x = 7 and 22 would be =RiskXtoP(PQ456,22) – RiskXtoP(PQ456,7).

How do I get the probability density, which Excel returns when the last argument of NORM.DIST is FALSE?

The probability density is simply the height of the curve at a given x value. Use RiskTheoXtoY instead of RiskTheoXtoP. (The RiskTheoXtoY function was added in @RISK 6.0 and is not available in @RISK 5.x.)

Last edited: 2017-05-04

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