I have no idea why the sexual activity survey, apart perhaps from useful in some way in genito-urinary medicine.

The sensor was worn on the wrist! This is a model-engineering forum not Facebook!

A good question, about members not often seen; and it applies to any club not just model-engineering.

Really, there is not much the club can do; though as far as I have experienced so far over many years, all the absences by deteriorating health have been flagged by the members themselves, or perhaps spouse; and all deaths by relatives.

My caving-clubs are affiliated indirectly to the British Caving Association and members can obtain third-party insurance directly from BCA by joining that as well or via the club. Your still pay the BCA subscription and insurance, at the same rate. However, members who have ceased active caving can still belong at a reduced rate to reflect much lower insurance; but still paying for the printed club magazines and towards upkeep of the club's physical assets.

I don't know if any model-engineering societies have a parallel arrangement. Mine doesn't, but the Club insurance covers only club activities and you need pay for property and third-party insurance for private use, yourself. Expensive it is too.

However that only accounts for the individual's continued existence.

It misses the point I raised.

You can be at your club weekly, whatever its interest and whatever your level of participation, but that still does not mean anyone else can necessarily be relied on to give accurate answers about your daily life outside of it, let alone your state of mind a decade previously.

That is the problem of the auxiliary part of the survey, not whether you are in this world or the next.

There's no evidence that the ELSA data is used for any commercial purposes linked to individuals; and the rubric does say what it's for! It is looking at trends in populations and needs at population level, not individual shopping habits. In fact it does not even ask those, but does ask about things like using public transport.

No need thanks to social-media, "smart"-'phones, supermarket "loyalty" cards, banks and insurance companies. shopping on-line for day-to-day goods, clothes and food. The big ad agencies who are the real clients of Facebook etc are unlikely to even notice our mail-ordering 3 end-mills and a two-foot length of brass bar; but the above channels are far more direct and relevant to them.

Besides, as far as I recall the questions don't ask about your identity or anything, and though it was nearly ten years ago I don't think you put your name on the sexual activity form. Age maybe, but that was the basic question anyway.

As it happens I've still to hear from the surveyors.

No I do not have that impression, but I do agree that politicians can and often do decide on poorly selected or understood data. The data themselves that are used by Governmental agencies and politicians are probably fine, collected and analysed properly. As you say, it's what's done with them that counts!.

Just a few minutes ago (a little before 9 am here), on BBC Radio Four's Today programme, an item on "smart"-'phones mentioned many ways we leave trails. They included so-called "smart" loudspeakers and even devices like the "Fitbit",

Though to be fair the latter was not accused of being an eavesdropper. It is not. It simply records when you are active or at rest, but not what you are doing or where. In one criminal case the accused was proven by his Fitbit to have active when he had claimed to have been in bed at home, supporting other evidence against him!

The massive collecting and trading of personal data are almost all commercial, but so many people walk straight into it by thinking everything has to be on-line all day and night, that they need a "smart-speaker", umpteen-G 'phone and wallet-full of shop cards, that they need plaster their lives across Facebook; and above all, have little or no sense of privacy or security.

We are being pushed relentlessly that way by the banks, supermarkets and some of the public services cramping our choices of how we use them; but I try to encourage them as little as possible. I certainly do not own a "smart"-'phone and 'speaker, and accounts on Twitter, Facebook and their ilk.

Thank you – I'd not taken it personally!