Paraméter

Paraméter is a term used across science and engineering to denote a quantity that defines or influences the behavior of a system, model, or function. The word paraméter originates from Greek para- “beside” and metron “measure,” reflecting its role as a characteristic input rather than a variable itself.

In mathematics and modeling, a parameter is a quantity that is typically treated as fixed within a particular analysis. It determines the form or behavior of the model but is not itself the primary variable being solved for. For example, in the line y = a x + b, a and b are parameters that set slope and intercept.

In statistics, a parameter describes a population property (for example, mean μ or variance σ^2). A statistic, by contrast, is computed from sample data to estimate the parameter. Parameter estimation uses methods such as maximum likelihood or Bayesian inference.

In programming, a parameter is a named value accepted by a function or procedure. The actual value passed is an argument. Parameters can be passed by value or by reference and may be required or optional.

In engineering, science, and machine learning, parameters are elements of models that may be fixed, calibrated, or learned from data. The set of all possible parameter values is called the parameter space; hyperparameters govern the learning process rather than the model’s direct outputs. Related terms include parameterization, nuisance parameters, and hyperparameters.