Jarque

Jarque is a surname of Spanish origin. It is borne by individuals in Spanish-speaking communities and appears in various contexts, including academia and professional fields. In statistical literature, the name Jarque is most often associated with the Jarque-Bera test, a widely used method for assessing whether a dataset deviates from a normal distribution.

The Jarque-Bera test was introduced by Carlos M. Jarque and Anil K. Bera in 1980. It combines information from the sample skewness and the sample kurtosis into a single statistic to evaluate normality. The test statistic is JB = n/6 [S^2 + (K − 3)^2/4], where n is the sample size, S is the sample skewness, and K is the sample kurtosis. Under the null hypothesis of normality and in large samples, JB approximately follows a chi-squared distribution with two degrees of freedom. This makes it a convenient tool for econometric and statistical applications, such as checking the normality of residuals in regression analyses or the suitability of time-series models.

The Jarque-Bera framework is implemented in many statistical software packages and remains popular for its simplicity and reliance on only two moments of the distribution. It is best used with sufficiently large samples and after careful consideration of data quality, as outliers and heavy tails can influence skewness and kurtosis and thus affect the test outcome.