Blockchain graphics signification

[Striffly]

Hello,

We are two French students lead make a graph representing the evolution of Bitcoin (many aspects) over time. For this, we use the graphics provided by the official website of Blockchain.

However, we seek to understand the meaning of two graphics, and the information they represent:
- "Output volume" : https://blockchain.info/en/charts/output-volume?timespan=all#
- "Estimated value of transactions" : https://blockchain.info/en/charts/estimated-transaction-volume?timespan=all

Any of you could it bring us clarification on the meaning of these graphics, and information represented on these?

Thank you very much

[franky1]

say i made a tx

1ABCDE 0.5  -> 1WXYZ 0.1
1ABCDE 0.5  -> 1ABCDE 0.4

output would show as 0.5 because thats the total used
estimated value would show as 0.1 because it recognises 0.4 went back to the sender as "change".

though the second one is not that accurate anymore, because most people do not "reuse address" so its hard to tell anymore which address is the "change" address belonging to the sender because they now use different addresses

eg

1ABCDE 0.5  -> 1HIJK 0.25
1ABCDE 0.5  -> 1LMNO 0.25

no way to know which one is the second party receiving the funds and which one is the originators new "change" address

so the estimated value, is now out of context and not a reliable observation as it would treat the second example as someone paying 2 different people and thus treat it as 0.5 going out and being spent