What is the difference between a normal and a Poisson distribution?

This table summarises the most important differences between normal distributions and Poisson distributions:

Characteristic	Normal	Poisson
Continuous or discrete	Continuous	Discrete
Parameter	Mean (µ) and standard deviation (σ)	Lambda (λ)
Shape	Bell-shaped	Depends on λ
Symmetry	Symmetrical	Asymmetrical (right-skewed). As λ increases, the asymmetry decreases.
Range	−∞ to ∞	0 to ∞

When the mean of a Poisson distribution is large (>10), it can be approximated by a normal distribution.

Poisson Distributions | Definition, Formula & Examples

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