As you might have observed volatility recently reached historically one of the highest values with VIX over 85%. Financial markets are in turmoil and many observers compare current events to 1987 market crash and the 2008 financial crisis. Please read the attached Wall Street Journal Article and any other articles you may find to discuss the extreme volatility observed in the market in the last few weeks. Think of the fundamental factors based on the news (coronovirus, oil shock, etc.) and at volatility trading strategies that were previously based on low volatility environment and became unprofitable leading to selling pressure and lack of liquidity.
Why it is in general important to test for non-stationarity in time series data before attempting to build an empirical model? ( I wrote a little relating to this question and it is attached. you can just add a sentence or two to it)
Please answer each question individually and use very easy words and be direct to the point