NSVariableStatusItemLength

NSVariableStat is a conceptual class designed to encapsulate descriptive statistics for a single numeric variable in a data analysis context. It is intended to be used within applications that collect and summarize data, such as scientific or business software built on the Cocoa framework. The class tracks basic aggregates for the variable, enabling quick calculation of common statistics without storing every sample.

Typical properties include variableName, count, sum, sumOfSquares, minimum, maximum, mean, variance, and standardDeviation. Some implementations expose confidenceInterval or standardError for a given confidence level.

Core methods allow incremental updates: addValue:, addValues:, reset. A mergeWithStat: method can combine results from another NSVariableStat, provided the variable names match or are compatible. There may be a toDictionary or description method to export results to JSON or a textual summary.

Implementation notes: To maintain numerical stability, most implementations update mean and variance using an online algorithm such as Welford's method. The class may support thread-safe updates or require external synchronization.

Usage considerations: NSVariableStat is intended for descriptive statistics, not hypothesis testing. It assumes numeric input and does not handle missing values unless explicitly supported. In Swift, a bridging type could provide similar functionality via generics.

See also: NSStatistics, NSDecimalNumber, NSValue, statistical analysis in Cocoa.