What is the propagation time in IOTA?

Question

For Bitcoin we have the following information about the propagation time from here:

12.6 seconds is the time it takes for a new block to propagate to 95% of nodes.

Is there any observation on how much time it takes for a transaction to propagate through the IOTA network?

If there is no statistical information, then, can we say that the propagation time must be less than bitcoin because of:
1- IOTA transactions/bundles are smaller than bitcoin blocks.
2- Each IOTA node broadcast the transaction as soon as receiving it, without sending INV and GetData messages as Bitcoin.

Answer 1

Is there any observation on how much time it takes for a transaction to propagate through the IOTA network?

There isn't, this is due to the lack of topology mapping on the IOTA network. So any arbitrary measurements between two nodes on the network may take N unknown hops before reaching its destination.

We can say that the propagation time must be less than bitcoin

That is a reasonable assumption. Additionally transactions are immediately propagated throughout the network, if they are are syntactically correct, rather than being placed in the mempool, or other caching mechanism, to be included in the next block.

Answer 2

Actually, that paper says,

"The median time until a node receives a block is 6.5 seconds whereas the mean is at 12.6 seconds. The long tail of the distribution means that even after 40 seconds there still are 5% of nodes that have not yet received the block"

So, if 5% of nodes have not yet received the block after 40s, then it stands to reason that 95% of the nodes have received the block within 40s, not 12.6.

There's another person that posted about this here: https://bitcoin.stackexchange.com/questions/10821/how-long-does-it-take-to-propagate-a-newly-created-block-to-the-entire-bitcoin-n