The study looked at stock market data from South Africa to see how well different models could predict changes in stock prices. They found that there were significant shifts in how volatile the stock market was over time, and that taking these shifts into account improved the accuracy of predictions. One model was better at predicting short-term changes, while another was better for longer-term predictions. Overall, models that considered these shifts in volatility did a better job of forecasting stock market movements than those that did not.