Rate parameter (lambda)
Definition
The single parameter of the Poisson distribution, equal to both the mean and the variance of the distribution. In forensic contexts lambda is the expected number of events (e.g., particles, rare alleles) per unit of time, area, or volume.
Related terms
- Likelihood ratio (LR)
- The ratio of two conditional probabilities: the probability of the observed evidence given the prosecution's hypothesis (same source), divided by the probability...
- Parameters
- The numerical constants that define the specific shape of a distribution within its family. The normal distribution has two parameters (mean and...
- Probability distribution
- A function that assigns probabilities to each possible value (or range of values) of a random variable. It fully characterises the uncertainty...
- Right skew
- A distribution is right-skewed when its tail extends further to the right than to the left. Many forensic measurement quantities (trace concentrations,...
- Shape and rate parameters
- The two parameters of the gamma distribution. The shape parameter controls how peaked or spread the distribution is; the rate parameter (sometimes...
Explained in
- Common Distributions in Forensic ScienceThe single parameter of the Poisson distribution, equal to both the mean and the variance of the distribution. In forensic contexts lambda is the expected numb...