As a result of the COVID-19 crisis there was a global move to home working, and increased reliance on video conference facilities such as those offered by Zoom Video Communications. At the same time there was a sudden increase in trading volumes for Zoom Technology shares. The latter is a company that sells electronic technology for mobile phones. It was soon established that this was a clear case of mistaken identity. Please propose and explain a test for establishing whether the markets are efficient in this case