Is it better to train staff internally or externally?

First priority to train a staff is internally to reduce cost and expenses...
Majorly it depend on training whether it is technical or non technical.
If resources are available for internal training then prefer it otherwise external.

Training should be internal and external.
So if you have the right resources (trainer, place, data, ..etc) it would be great to make the training internally.
But, if you have a new kind of equipment or program or a new business strategy, I'd prefer to make it external with a more experienced trainer in the such new matters.

Depending on the type of position  I would say do a combination of both, and one not necessarily more than the other if the performance measures are based on knowledge that cannot be gained from simply on the job training. I have had positions that immediately required an initial external training, and others that left me completely open to learn on the job and allowed external training through the process (some self encouraged and others mandatory. Both were very integral in my overall experience and I benefit greatly as a result of them.

To train staff internally or externally depend mainly on available budget and needs.
It could be done internally if expertise available, alternatively external source could be a better option as they are up to date in selling required skills.

http://bluespottraining.blogspot.com/2012/09/internal-or-external-training-which.html