# 📢 Mean Age

At Santiment we just released a brand new metric: Mean dollar invested age. Together with Mean coin age that we released several months ago this gives us a radically new way to look at investor behavior on the blockchain.

Here are the graphs for Bitcoin:

But what is this mean age? It's something very simple. For each coin we see how long it has stayed at its current address and we compute the average of all those ages. The difference between "coin age" and "dollar age" comes from the different way that we compute the averages.

Let's look at an example. We have two Bitcoin HODLers: Alice 👩 and Bob 👨.

Alice bought 1 BTC on January 1st, 2017, while Bob bought 0.5 BTC on January 1st, 2018. If they are still HODLing, 👩 will have right now (on September 20th, 2019) 1 BTC whose age is 992 days, while 👨 will have 0.5 BTC whose age is 627 days. So the mean coin age is:

The mean dollar age shows what is the average age of the dollars invested to buy the coins. On January 1st 2017 1 BTC was worth 💲958.70, and one year later it was worth 💲13,391.80. So the the mean dollar invested age for 👩 and 👨 is:

The mean coin age is closer to the age of Alice's investment, because it was bigger in terms of BTC, but the mean dollar age was much closer to Bob's investment because it was bigger in dollar terms.

Let's look back to the Bitcoin mean age chart: