Should I refer to an instance or a class method in a loop that creates objects?

I am working on importing a .csv file into a Ruby on Rails app. The importer will create a new database record from each row of the file.

class Invoice < ApplicationRecord

  def self.import(file)
    output_log = []
    CSV.foreach(file.path) do |row|
      output_log << some_method_name(row)
    end
    return output_log
  end

end

I want all the complexity of data validation, record creation, and error reporting to be tucked away in another method, rather than cluttering up my import method. I'm calling some_method_name as an example. What should I really be calling?

Two possibilities occur to me. An instance method:

output_log << Invoice.new.populate_from_row(row)

Or, a class method:

output_log << Invoice.create_from_row(row)

(Either would return a string that logs success or failure.)

Both will work, but which makes more sense? Is there some design principle or pattern that should inform me about how to choose?