I am currently faced with the challenge to measure integration speed of an acquisition or a merger with secondary data. Usually companies do not communicate once a target has been integrated successfully. They only announce for instance that an M&A deal has been signed (this would be the starting date and easy to find online). However, how can I find out when the company was fully integrated? I am focusing on Dutch M&A deals and it seems that Dutch companies do not communicate about it much apart from when a deal has been signed. Sometimes it is possible to find out when a target ceased to exist but this too is quite difficult. I saw in most papers that surveys were used but due to my time constraint it is a too high risk to send out surveys to Dutch corporate M&A teams due to the high possibility of a low response rate. I also saw in one paper that they have used survival analysis. However, I could not make sense in that paper how they specifically calculated integration speed for each deal. If anyone has an idea or knows a paper that has done that with secondary data, I would appreciate any help.