I was part of an NHS longitudinal study for about 30 years but dropped out. On the last visit I was asked to carry out an IQ test. The woman entered my home and passed me a laptop and said "Start when you like". Then handed me the laptop. She went outside for 10 minutes to smoke thinking she would be able to go on return. But then noticed on the screen I hadn't started. I said I waited until she came back in. I completed the IQ test in perhaps two minutes.

I dropped out because I wrote and asked them what use had been made of my data but they didn't reply. At the time there were serious NHS issues and I thought our data was making no difference.