Explore the evidence
Theoretical and simulated delivery times
Included areaNormal densitySimulated observations
Environment 06 · Continuous-threshold decision lab
What proportion crosses a practical threshold?
A normal model uses a mean and standard deviation to describe continuous measurements. Explore delivery times, package-fill weights, and assessment scores.
FrameExploreInterpretDecide
Interpret
A z-score locates the threshold
Decide
Evaluate the service promise
Compare the probability of meeting the target with the organization’s promised service level.
See the mathematics and assumptions
For X ~ Normal(μ,σ²), standardize with z=(x−μ)/σ and use the standard normal distribution. For a continuous variable, P(X=x)=0; probabilities correspond to areas over intervals. Use the model only when the distribution is reasonably continuous, symmetric, and bell-shaped.