A few important filters to note that can be applied to various scenarios to alter the event impact averages:
1) Sectors - not all sectors react the same. For instance, investors often punish tech companies for giving up on growth and doing stock buybacks, while they reward financial and industrial companies for doing buybacks. Similarly, large tech companies that are mildly profitable or not profitable are rewarded for laying people off, while it may be a sign of trouble ahead for other sectors like Finance.
2) Earnings - stock of companies with positive earnings may react differently than those with negative earnings when faced when an event like layoffs and CEO departures. Poor performing companies stock jumps when CEO's depart.
3) Market Cap - the size of the company matters often. Larger companies can absorb bad news more easily because they are more established and more stable (e.g. CEO departures, dividend cuts). It's less dire than when something bad happens to a smaller company. Conversely, good news can more positively impact smaller companies (e.g. Billion dollar contracts).
4) Revenue Growth - companies growing revenues are more attractive than those not growing revenues
5) Volume - trading volume is a way to measure a stock's popularity. The more volume, the more the stock can react to an event as more people hear about it. The reactions are also faster, often, whereas other lesser known companies may not get any media coverage.
6) Dividend Yield - dividend increases are great bullish events, but they will impact the price moves on stock that already have a decent dividend yield of .8% or more.