# How does error accumulate when entangling two distant qubits with limited connectivity?

My goal is to minimize accumulated error when entangling two qubits that cannot be entangled via a single native two qubit gate operation.

I have a coupling map/graph for the qubits of an IBM quantum computer. Two nodes that share an edge can be used for a native two qubit gate operation. This is required to entangle the qubits. If I don't have a connection between two potentially distant (many qubits and their edges needed to connect the two) qubits, I have to use these intermediate qubits (for swaps) to entangle the two distant qubits. As far as I understood.

My question is the following. Let's say I want to perform a CNOT between $$q_0$$ and $$q_n$$ but the qubits are connected like a chain: $$\{(q_0, q_1), (q_1, q_2),\dots, (q_{n-1}, q_n)\}.$$ I would first CNOT($$q_0, q_1$$) then SWAP($$q_1, q_2$$), then SWAP($$q_2, q_3$$), and so on to finally SWAP($$q_{n-1}, q_n$$). The CNOT and SWAP operations require the use of the two qubit gate operation. If I know how large the two qubit gate error for each pair ($$q_i, q_{i+1}$$) is and how the CNOT and SWAP are decomposed into native gates, how can I compute the total accumulated error?