The Magpies worked long and hard during pre-season to attract a series of targets to Tyneside, but ultimately signed just one senior player, Dutch midfielder Vurnon Anita, as the likes of Lille full-back Mathieu Debuchy and FC Twente defender Douglas stayed put despite protracted negotiations.
Answering questions posed by readers of the Evening Chronicle, the city's evening newspaper, Pardew admitted he, owner Mike Ashley and managing director Derek Llambias, with the help of chief scout Graham Carr, should have recruited one more man to go straight into the first-team squad.
Pardew said: "Myself, Mike and Derek all agree we should have bought one more senior player in here. For whatever reason, it did not happen.
"We have learnt from that, and that is what comes from the luxury which is the security of the owner.
"The owner has great faith in my ability and I have to reward that with what I think when we make an error and say we have made a mistake.
"He accepts that and as a team we have to learn from it. Myself, Graham, Derek and Mike needed another player in and we did not get him.
"But it is not Graham's fault, Derek's fault or Mike's fault or mine - it is a collective thing and we have to take that all on the chin. We got that wrong."
Newcastle will attempt to address that imbalance next month and have already been linked once again with Debuchy and Douglas, as well as Marseille striker Loic Remy.
But Pardew, who reiterated his interest in bringing Andy Carroll back to St James' Park - although he does not believe he will be available - is not expecting to make several signings unless he loses players with striker Demba Ba's future once again in the spotlight and speculation circulating about potential interest in midfielders Cheick Tiote and Yohan Cabaye.
He said: "It is a difficult window, but I think we would like to get - definitely - one player in and not lose anybody.
"It could be we lose a player, you never know. I lost Andy Carroll in this window, and in a situation that was not too dissimilar to what I am in now two years ago - maybe it was a bit better.
"However, if that is the case, then we need two players, and if we lose two, then we need three. That will be difficult in this window.
"I cannot see two players leaving, but you can never count on that."