About this question
Medium · statistical_analysis · Quant Researcher interview question · ljung_box, autocorrelation, hypothesis_testing
The Ljung-Box test is a statistical procedure for determining whether any of a group of autocorrelations of a time series are different from zero. It is a portmanteau test, meaning it tests the overall randomness based on a number of lags. In quantitative finance, this test is essential for validating time series models, such as ARIMA or GARCH, by ensuring their residuals exhibit no remaining serial correlation, a key assumption of a well-specified model. Task Implement the function ljung_box_t