I wonder, is it possible to analyze the blockchain to get an idea of the average age of coins being bought/sold right now on exchanges compared to the overall average age of bitcoins? It might be possible, for example, to determine that most selling right now is by miners needing to pay their bills, while most investors are sitting tight.
That should be possible to some extent: exchange addresses can be guesstimated through taint analysis, and funds from miners are trivial to identify.
However there would be some significant bias as funds traded on an exchange don't necessarily leave that exchange, only a small fractions does through withdrawals and arbitrage bots, and the transactions within an exchange are not visible on the blockchain.
Also you would have heavy background "noise" from exchanges "withdrawing" to cold wallets or consolidating coins for auditing purposes, which on first analysis might be difficult to differentiate from investors withdrawing from an exchange.
But it might be possible to devise some rough indicator, hmmm...
This would likely not be possible with a strong degree of certainty. You need to remember that not all bitcoin that passes through an exchange will go to their cold wallet/cold storage. It would be very well possible that someone selling bitcoin on say btc-e would deposit their bitcoin to their deposit address and then someone who recently purchased bitcoin would withdraw their newly purchased bitcoin and the inputs from the previous person's deposit address would be used to fund the transaction
